draft-ietf-sipcore-sip-push-21.txt   draft-ietf-sipcore-sip-push-22.txt 
SIPCORE Working Group C. Holmberg SIPCORE Working Group C. Holmberg
Internet-Draft Ericsson Internet-Draft Ericsson
Intended status: Standards Track M. Arnold Intended status: Standards Track M. Arnold
Expires: June 10, 2019 Metaswitch Networks Expires: July 20, 2019 Metaswitch Networks
December 7, 2018 January 16, 2019
Push Notification with the Session Initiation Protocol (SIP) Push Notification with the Session Initiation Protocol (SIP)
draft-ietf-sipcore-sip-push-21 draft-ietf-sipcore-sip-push-22
Abstract Abstract
This document describes how a Push Notification Service (PNS) can be This document describes how a Push Notification Service (PNS) can be
used to wake suspended Session Initiation Protocol (SIP) User Agents used to wake suspended Session Initiation Protocol (SIP) User Agents
(UAs), using push notifications, for the UA to be able to send (UAs), using push notifications, for the UA to be able to send
binding-refresh REGISTER requests and to receive receive incoming SIP binding-refresh REGISTER requests and to receive receive incoming SIP
requests. The document defines new SIP URI parameters and new requests. The document defines new SIP URI parameters and new
feature-capability indicators that can be used in SIP messages to feature-capability indicators that can be used in SIP messages to
indicate support of the mechanism defined in this document, to indicate support of the mechanism defined in this document, to
exchange PNS information between the SIP User Agent (UA) and the SIP exchange PNS information between the SIP User Agent (UA) and the SIP
entity that will request push notifications towards the UA, and to entity that will request that push notifications are sent to the UA,
trigger such push notification requests. and to trigger such push notification requests.
Status of This Memo Status of This Memo
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 6 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 7
3. Push Resource ID (PRID) . . . . . . . . . . . . . . . . . . . 6 3. Push Resource ID (PRID) . . . . . . . . . . . . . . . . . . . 7
4. SIP User Agent (UA) Behavior . . . . . . . . . . . . . . . . 7 4. SIP User Agent (UA) Behavior . . . . . . . . . . . . . . . . 7
4.1. Request Push Notifications from Network . . . . . . . . . 7 4.1. Request Push Notifications from Network . . . . . . . . . 7
4.2. Query Network Push Notification Capabilities . . . . . . 10 4.2. Query Network Push Notification Capabilities . . . . . . 10
5. SIP Proxy Behavior . . . . . . . . . . . . . . . . . . . . . 10 5. SIP Proxy Behavior . . . . . . . . . . . . . . . . . . . . . 11
5.1. PNS Provider . . . . . . . . . . . . . . . . . . . . . . 10 5.1. PNS Provider . . . . . . . . . . . . . . . . . . . . . . 11
5.2. Trigger Periodic Binding Refresh . . . . . . . . . . . . 10 5.2. Trigger Periodic Binding Refresh . . . . . . . . . . . . 11
5.3. SIP Requests . . . . . . . . . . . . . . . . . . . . . . 11 5.3. SIP Requests . . . . . . . . . . . . . . . . . . . . . . 12
5.3.1. REGISTER . . . . . . . . . . . . . . . . . . . . . . 11 5.3.1. REGISTER . . . . . . . . . . . . . . . . . . . . . . 12
5.3.2. Initial Request for Dialog or Stand-Alone Request . . 13 5.3.2. Initial Request for Dialog or Stand-Alone Request . . 14
6. Support Of Longlived SIP Dialogs . . . . . . . . . . . . . . 16 6. Support Of Longlived SIP Dialogs . . . . . . . . . . . . . . 17
6.1. SIP UA Behavior . . . . . . . . . . . . . . . . . . . . . 16 6.1. SIP UA Behavior . . . . . . . . . . . . . . . . . . . . . 19
6.1.1. Initial Request for Dialog . . . . . . . . . . . . . 16 6.1.1. Initial Request for Dialog . . . . . . . . . . . . . 19
6.2. SIP Proxy Behavior . . . . . . . . . . . . . . . . . . . 17 6.2. SIP Proxy Behavior . . . . . . . . . . . . . . . . . . . 19
6.2.1. REGISTER . . . . . . . . . . . . . . . . . . . . . . 17 6.2.1. REGISTER . . . . . . . . . . . . . . . . . . . . . . 19
6.2.2. Initial Request for Dialog . . . . . . . . . . . . . 17 6.2.2. Initial Request for Dialog . . . . . . . . . . . . . 20
6.2.3. Mid-Dialog Request . . . . . . . . . . . . . . . . . 18 6.2.3. Mid-Dialog Request . . . . . . . . . . . . . . . . . 20
7. Support Of SIP Replaces . . . . . . . . . . . . . . . . . . . 18 7. Support Of SIP Replaces . . . . . . . . . . . . . . . . . . . 21
8. Grammar . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 8. Grammar . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
8.1. 555 (Push Notification Service Not Supported) Response 8.1. 555 (Push Notification Service Not Supported) Response
Code . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Code . . . . . . . . . . . . . . . . . . . . . . . . . . 21
8.2. sip.pns Feature-Capability Indicator . . . . . . . . . . 19 8.2. sip.pns Feature-Capability Indicator . . . . . . . . . . 21
8.3. sip.vapid Feature-Capability Indicator . . . . . . . . . 19 8.3. sip.vapid Feature-Capability Indicator . . . . . . . . . 22
8.4. sip.pnsreg Feature-Capability Indicator . . . . . . . . . 20 8.4. sip.pnsreg Feature-Capability Indicator . . . . . . . . . 22
8.5. sip.pnsreg Media Feature Tag . . . . . . . . . . . . . . 20 8.5. sip.pnsreg Media Feature Tag . . . . . . . . . . . . . . 23
8.6. sip.pnspurr Feature-Capability Indicator . . . . . . . . 21 8.6. sip.pnspurr Feature-Capability Indicator . . . . . . . . 23
8.7. SIP URI Parameters . . . . . . . . . . . . . . . . . . . 21 8.7. SIP URI Parameters . . . . . . . . . . . . . . . . . . . 23
9. PNS Registration Requirements . . . . . . . . . . . . . . . . 21 9. PNS Registration Requirements . . . . . . . . . . . . . . . . 24
10. pn-provider, pn-param and pn-prid URI Parameters for Apple 10. pn-provider, pn-param and pn-prid URI Parameters for Apple
Push Notification service . . . . . . . . . . . . . . . . . . 22 Push Notification service . . . . . . . . . . . . . . . . . . 24
11. pn-provider, pn-param and pn-prid URI Parameters for Google 11. pn-provider, pn-param and pn-prid URI Parameters for Google
Firebase Cloud Messaging (FCM) push notification service . . 22 Firebase Cloud Messaging (FCM) push notification service . . 25
12. pn-provider, pn-param and pn-prid URI Parameters for RFC 8030 12. pn-provider, pn-param and pn-prid URI Parameters for RFC 8030
(Generic Event Delivery Using HTTP Push) . . . . . . . . . . 23 (Generic Event Delivery Using HTTP Push) . . . . . . . . . . 25
13. Security Considerations . . . . . . . . . . . . . . . . . . . 23 13. Security Considerations . . . . . . . . . . . . . . . . . . . 26
14. IANA considerations . . . . . . . . . . . . . . . . . . . . . 24 14. IANA considerations . . . . . . . . . . . . . . . . . . . . . 27
14.1. SIP URI Parameters . . . . . . . . . . . . . . . . . . . 24 14.1. SIP URI Parameters . . . . . . . . . . . . . . . . . . . 27
14.1.1. pn-provider . . . . . . . . . . . . . . . . . . . . 24 14.1.1. pn-provider . . . . . . . . . . . . . . . . . . . . 27
14.1.2. pn-param . . . . . . . . . . . . . . . . . . . . . . 24 14.1.2. pn-param . . . . . . . . . . . . . . . . . . . . . . 27
14.1.3. pn-prid . . . . . . . . . . . . . . . . . . . . . . 24 14.1.3. pn-prid . . . . . . . . . . . . . . . . . . . . . . 28
14.1.4. pn-purr . . . . . . . . . . . . . . . . . . . . . . 25 14.1.4. pn-purr . . . . . . . . . . . . . . . . . . . . . . 28
14.2. SIP Response Codes . . . . . . . . . . . . . . . . . . . 25 14.2. SIP Response Codes . . . . . . . . . . . . . . . . . . . 28
14.2.1. 555 (Push Notification Service Not Supported) . . . 25 14.2.1. 555 (Push Notification Service Not Supported) . . . 28
14.3. SIP Global Feature-Capability Indicator . . . . . . . . 25 14.3. SIP Global Feature-Capability Indicator . . . . . . . . 28
14.3.1. sip.pns . . . . . . . . . . . . . . . . . . . . . . 25 14.3.1. sip.pns . . . . . . . . . . . . . . . . . . . . . . 28
14.3.2. sip.vapid . . . . . . . . . . . . . . . . . . . . . 26 14.3.2. sip.vapid . . . . . . . . . . . . . . . . . . . . . 29
14.3.3. sip.pnsreg . . . . . . . . . . . . . . . . . . . . . 26 14.3.3. sip.pnsreg . . . . . . . . . . . . . . . . . . . . . 29
14.3.4. sip.pnspurr . . . . . . . . . . . . . . . . . . . . 27 14.3.4. sip.pnspurr . . . . . . . . . . . . . . . . . . . . 30
14.4. SIP Media Feature Tag . . . . . . . . . . . . . . . . . 28 14.4. SIP Media Feature Tag . . . . . . . . . . . . . . . . . 31
14.4.1. sip.pnsreg . . . . . . . . . . . . . . . . . . . . . 28 14.4.1. sip.pnsreg . . . . . . . . . . . . . . . . . . . . . 31
14.5. PNS Sub-registry Establishment . . . . . . . . . . . . . 28 14.5. PNS Sub-registry Establishment . . . . . . . . . . . . . 31
15. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 29 15. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 32
16. References . . . . . . . . . . . . . . . . . . . . . . . . . 29 16. References . . . . . . . . . . . . . . . . . . . . . . . . . 32
16.1. Normative References . . . . . . . . . . . . . . . . . . 29 16.1. Normative References . . . . . . . . . . . . . . . . . . 32
16.2. Informative References . . . . . . . . . . . . . . . . . 30 16.2. Informative References . . . . . . . . . . . . . . . . . 34
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 31 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 35
1. Introduction 1. Introduction
In order to save resources (e.g., battery life) some devices In order to save resources (e.g., battery life) some devices
(especially mobile devices) and operating systems will suspend (especially mobile devices) and operating systems will suspend
applications when not used. In some cases, internal timers cannot be applications when not used. In some cases, internal timers cannot be
used to wake such applications, nor will incoming network traffic used to wake such applications, nor will incoming network traffic
wake the application. Instead, one way to wake the application is by wake the application. Instead, one way to wake the application is by
using a Push Notification Service (PNS). Typically each operating using a Push Notification Service (PNS). A PNS is a service from
system uses a dedicated PNS. For example, Apple iOS devices use the where a user application can receive messages, referred to as push
Apple Push Notification service (APNs) while Android devices use the notifications, requested by other applications. Push notifications
Firebase Cloud Messaging (FCM) service. might contain payload data, depending on the application. An
application can requests that a push notification is sent to a single
user application, or to multiple user applications.
Typically each operating system uses a dedicated PNS. For example,
Apple iOS devices use the Apple Push Notification service (APNs)
while Android devices use the Firebase Cloud Messaging (FCM) service.
Because of the restrictions above, Session Initiation Protocol (SIP) Because of the restrictions above, Session Initiation Protocol (SIP)
User Agents (UAs) [RFC3261] can not be awoken, in order to send User Agents (UAs) [RFC3261] can not be awoken, in order to send
binding-refresh SIP REGISTER requests and to receive incoming SIP binding-refresh SIP REGISTER requests and to receive incoming SIP
requests, without using a PNS to wake the UA in order to perform requests, without using a PNS to wake the UA in order to perform
those functions. those functions.
Also, without being able to use internal timers in order to wake Also, without being able to use internal timers in order to wake
applications, a UA will not be able to maintain connections e.g., applications, a UA will not be able to maintain connections e.g.,
using the SIP Outbound Mechanism [RFC5626], as it requires the UA to using the SIP Outbound Mechanism [RFC5626], as it requires the UA to
send periodic keep-alive messages. send periodic keep-alive messages.
This document describes how PNSs can be used to wake suspended UAs, This document describes how PNSs can be used to wake suspended UAs,
using push notifications, to be able to send binding-refresh REGISTER using push notifications, to be able to send binding-refresh REGISTER
requests and to receive incoming SIP requests. The document defines requests and to receive incoming SIP requests. The document defines
new SIP URI parameters and new feature-capability indicators new SIP URI parameters and new feature-capability indicators
[RFC6809] that can be used in SIP messages to indicate support of the [RFC6809] that can be used in SIP messages to indicate support of the
mechanism defined in this document, to exchange PNS information mechanism defined in this document, to exchange PNS information
between the UA and the SIP entity (realized as a SIP proxy in this between the UA and the SIP entity (realized as a SIP proxy in this
document) that will request push notifications towards the UA, and to document) that will request that push notifications are sent to the
request such push notification requests. UA, and to request such push notification requests.
NOTE: Even if a UA is able to be awakened by other means than NOTE: Even if a UA is able to be awakened by other means than
receiving push notifications (e.g., by using internal timers) in receiving push notifications (e.g., by using internal timers) in
order to send periodic binding-refresh REGISTER requests, it might order to send periodic binding-refresh REGISTER requests, it might
still be useful to suspend the application between the sending of still be useful to suspend the application between the sending of
binding-refresh requests (as it will save battery life) and use push binding-refresh requests (as it will save battery life) and use push
notifications to wake the UA when an incoming SIP request UA arrives. notifications to wake the UA when an incoming SIP request UA arrives.
When a UA registers to a PNS, it will receive a unique Push Resource When a UA registers to a PNS, it will receive a unique Push Resource
ID (PRID) associated with the push notification registration. The UA ID (PRID) associated with the push notification registration. The UA
will use a REGISTER request to provide the PRID to the SIP proxy that will use a REGISTER request to provide the PRID to the SIP proxy that
will request push notifications towards the UA. will request push that notifications are sent to the UA.
When the proxy receives a SIP request for a new dialog or a stand- When the proxy receives a SIP request for a new dialog or a stand-
alone SIP request addressed towards a UA, or when the proxy alone SIP request addressed towards a UA, or when the proxy
determines that the UA needs to send a binding-refresh REGISTER determines that the UA needs to send a binding-refresh REGISTER
request, the proxy will request a push notification towards the UA, request, the proxy will request that a push notification is sent to
using the PNS of the UA. Once the UA receives the push notification, the UA, using the PNS of the UA. Once the UA receives the push
it will be able to send a binding-refresh REGISTER request and notification, it will be able to send a binding-refresh REGISTER
receive the incoming SIP request. The proxy will receive the request and receive the incoming SIP request. The proxy will receive
REGISTER request. If the push notification request was triggered by the REGISTER request. If the push notification request was triggered
a SIP request addressed towards the UA (see above), once the REGISTER by a SIP request addressed towards the UA (see above), once the
request has been accepted by the SIP registrar [RFC3261], and the REGISTER request has been accepted by the SIP registrar [RFC3261],
associated SIP 2xx response has been forwarded by the proxy towards and the associated SIP 2xx response has been forwarded by the proxy
the UA, the proxy can forward the SIP request towards the UA using towards the UA, the proxy can forward the SIP request towards the UA
normal SIP routing procedures. In some cases the proxy can forward using normal SIP routing procedures. In some cases the proxy can
the SIP request without waiting for the SIP 2xx response to the forward the SIP request without waiting for the SIP 2xx response to
REGISTER request. Note that this mechanism necessarily adds delay to the REGISTER request. Note that this mechanism necessarily adds
responding to requests requiring push notification. The consequences delay to responding to requests requiring push notification. The
of that delay are discussed in Section 5.3.2. consequences of that delay are discussed in Section 5.3.2.
If there are Network Address Translators (NATs) between the UA and
the proxy, the REGISTER request sent by the UA will create NAT
bindings that will allow the incoming SIP request that triggered the
push notification to reach the UA.
NOTE: The lifetime of any NAT binding created by the REGISTER request
only needs to be long enough in order for the SIP request that
triggered the push notification to reach the UA.
Different PNSs exist today. Some are based on the standardized Different PNSs exist today. Some are based on the standardized
mechanism defined in [RFC8030], while others are proprietary (e.g., mechanism defined in [RFC8030], while others are proprietary (e.g.,
the Apple Push Notification service). Figure 1 shows the generic the Apple Push Notification service). Figure 1 shows the generic
push notification architecture supported by the mechanism in this push notification architecture supported by the mechanism in this
document. document.
Each PNS uses PNS-specific terminology and function names. The Each PNS uses PNS-specific terminology and function names. The
terminology in this document is meant to be PNS-independent. If the terminology in this document is meant to be PNS-independent. If the
PNS is based on [RFC8030], the SIP proxy takes the role of the PNS is based on [RFC8030], the SIP proxy takes the role of the
skipping to change at page 5, line 11 skipping to change at page 5, line 25
The proxy MUST be in the signalling path of REGISTER requests sent by The proxy MUST be in the signalling path of REGISTER requests sent by
the UA towards the registrar, and of SIP requests (for a new dialog the UA towards the registrar, and of SIP requests (for a new dialog
or a stand-alone) forwarded by the proxy responsible for the UA's or a stand-alone) forwarded by the proxy responsible for the UA's
domain (sometimes referred to as home proxy, S-CSCF, etc) towards the domain (sometimes referred to as home proxy, S-CSCF, etc) towards the
UA. The proxy can also be co-located with the proxy responsible for UA. The proxy can also be co-located with the proxy responsible for
the UA's domain. This will also ensure that the Request-URI of SIP the UA's domain. This will also ensure that the Request-URI of SIP
requests (for a new dialog or a stand-alone) can be matched against requests (for a new dialog or a stand-alone) can be matched against
contacts in REGISTER requests. contacts in REGISTER requests.
+--------+ +--------------+ +-----------------+ +--------+ +---------+ +-----------+ +-------------+
| SIP UA | | Push Service | | SIP Proxy | | | | | | | | SIP |
+--------+ +--------------+ +-----------------+ | SIP UA | | Push | | SIP Proxy | | Registrar / |
| | | | | | Service | | | | Home Proxy |
| Subscribe | | +--------+ +---------+ +-----------+ +-------------+
|--------------------->| | | | | |
| | | | Subscribe | | |
| Push Resource ID | | |---------------->| | |
|<---------------------| | | | | |
| | | | PRID | | |
| SIP REGISTER (Push Resource ID) | |<----------------| | |
|===============================================>| | | | |
| | | SIP REGISTER | SIP REGISTER (PRID) | |
| | |============> |===================================>| |
| | | | | |SIP REGISTER (PRID)|
| | | SIP 200 OK | | |==================>|
| | |<============ | | | |
| SIP 200 OK | | | | | SIP 200 OK |
|<===============================================| | | |<==================|
| | | | SIP 200 OK | | |
| | | |<===================================| |
| | | | | | |
| | | SIP INVITE | | | |
| | Push Message |<============ | | | |
| | (Push Resource ID) | | | | SIP INVITE (PRID) |
| Push Message |<------------------------| | | |<==================|
| (Push Resource ID) | | | | | |
|<---------------------| | | |Push Request (PRID) |
| | | | |<-----------------| |
| SIP REGISTER (Push Resource ID) | |Push Message (PRID) | |
|===============================================>| |<----------------| | |
| | | SIP REGISTER | | | |
| | |============> | SIP REGISTER (PRID) | |
| | | |===================================>| |
| | | SIP 200 OK | | |SIP REGISTER (PRID)|
| | |<============ | | |==================>|
| SIP 200 OK | | | | | |
|<===============================================| | | | SIP 200 OK |
| | | | | |<==================|
| SIP INVITE | | | SIP 200 OK | | |
|<===============================================| |<===================================| |
| | | | | | |
| SIP INVITE | | |
|<===================================| |
| | | |
------- Push Notification API ------- Push Notification API
======= SIP ======= SIP
Figure 1: SIP Push Information Flow
Example of a SIP REGISTER request in the flow above:
REGISTER sip:alice@example.com SIP/2.0 REGISTER sip:alice@example.com SIP/2.0
Via: SIP/2.0/TCP alicemobile.example.com:5060;branch=z9hG4bKnashds7 Via: SIP/2.0/TCP alicemobile.example.com:5060;branch=z9hG4bKnashds7
Max-Forwards: 70 Max-Forwards: 70
To: Alice <sip:alice@example.com> To: Alice <sip:alice@example.com>
From: Alice <sip:alice@example.com>;tag=456248 From: Alice <sip:alice@example.com>;tag=456248
Call-ID: 843817637684230@998sdasdh09 Call-ID: 843817637684230@998sdasdh09
CSeq: 1826 REGISTER CSeq: 1826 REGISTER
Contact: <sip:alice@alicemobile.example.com; Contact: <sip:alice@alicemobile.example.com;
pn-provider=acme; pn-provider=acme;
pn-param=acme-param; pn-param=acme-param;
pn-prid=ZTY4ZDJlMzODE1NmUgKi0K> pn-prid=ZTY4ZDJlMzODE1NmUgKi0K>
Expires: 7200 Expires: 7200
Content-Length: 0 Content-Length: 0
Figure 1: SIP Push Notification Architecture Figure 2: SIP REGISTER Example
2. Conventions 2. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. Push Resource ID (PRID) 3. Push Resource ID (PRID)
skipping to change at page 7, line 37 skipping to change at page 8, line 27
one for IPv6), since a push notification will trigger to UA to one for IPv6), since a push notification will trigger to UA to
refresh all bindings, it is preferable if one can ensure that all refresh all bindings, it is preferable if one can ensure that all
bindings expire at the same time. That will help preventing that bindings expire at the same time. That will help preventing that
some bindings are refreshed earlier than needed. some bindings are refreshed earlier than needed.
When the UA receives a 2xx response to the REGISTER request, if the When the UA receives a 2xx response to the REGISTER request, if the
response contains a Feature-Caps header field [RFC6809] with a response contains a Feature-Caps header field [RFC6809] with a
'sip.pns' feature-capability indicator with a parameter value 'sip.pns' feature-capability indicator with a parameter value
identifying the same type of PNS that was identified by the pn- identifying the same type of PNS that was identified by the pn-
provider URI parameter in the REGISTER request, the UA can assume provider URI parameter in the REGISTER request, the UA can assume
that a SIP proxy will request push notifications towards the UA. In that a SIP proxy will request that a push notification is sent to the
other cases, the UA MUST NOT assume that push notifications will be UA. In other cases, the UA MUST NOT assume that the proxy will
requested, and the actions taken by the UA might be dependent on request that push notifications is sent to the UA, and the actions
implementation or deployment architecture, and are outside the scope taken by the UA might be dependent on implementation or deployment
of this document. architecture, and are outside the scope of this document.
In addition, if the response contains a Feature-Caps header field In addition, if the response contains a Feature-Caps header field
with a 'sip.vapid' feature-capability indicator, the proxy supports with a 'sip.vapid' feature-capability indicator, the proxy supports
use of the Voluntary Application Server Identification (VAPID) use of the Voluntary Application Server Identification (VAPID)
mechanism [RFC8292] to restrict push notifications to the proxy. mechanism [RFC8292] to restrict push notifications to the proxy.
NOTE: The VAPID specific procedures of the SIP UA are outside the NOTE: The VAPID specific procedures of the SIP UA are outside the
scope of this document. scope of this document.
When the UA receives a push notification, it MUST send a binding- When the UA receives a push notification, it MUST send a binding-
refresh REGISTER request, using normal SIP procedures. If there are refresh REGISTER request, using normal SIP procedures. Once the UA
Network Address Translators (NATs) between the UA and the proxy, the has received a 2xx response to the REGISTER request, the UA might
REGISTER request will create NAT bindings that will allow incoming receive a SIP request for a new dialog (e.g., a SIP INVITE), or a
SIP requests to reach the UA. Once the UA has received a 2xx stand-alone SIP request (e.g., a SIP MESSAGE), if such SIP request
response to the REGISTER request, the UA might receive a SIP request triggered the push notification. Note that, depending on which
for a new dialog (e.g., a SIP INVITE), or a stand-alone SIP request transport protocol is used, the SIP request might reach the UA before
(e.g., a SIP MESSAGE), if such SIP request triggered the push the REGISTER response.
notification request. Note that, depending on which transport
protocol is used, the SIP request might reach the UA before the
REGISTER response.
NOTE: The lifetime of any NAT binding created by the REGISTER request
only needs to be long enough in order for the SIP request that
triggered the push notification to reach the UA.
If the SIP UA has created multiple bindings (e.g., one for IPv4 and If the SIP UA has created multiple bindings (e.g., one for IPv4 and
one for IPv6), the UA MUST send a binding-refresh REGISTER request one for IPv6), the UA MUST send a binding-refresh REGISTER request
for each of those bindings when it receives a push notification. for each of those bindings when it receives a push notification.
If the UA is able to send binding-refresh REGISTER requests using a If the UA is able to send binding-refresh REGISTER requests using a
non-push mechanism (e.g., using an internal timer that periodically non-push mechanism (e.g., using an internal timer that periodically
wakes the UA), the UA MUST insert a 'sip.pnsreg' media feature tag wakes the UA), the UA MUST insert a 'sip.pnsreg' media feature tag
[RFC3840] in each Contact header field URI of each REGISTER request. [RFC3840] in each Contact header field URI of each REGISTER request.
Then, if the response to the REGISTER request contains a 'sip.pnsreg' Then, if the response to the REGISTER request contains a 'sip.pnsreg'
feature-capability indicator with an indicator value, the UA feature-capability indicator with an indicator value, the UA
refreshes the binding prior to the binding expires. The indicator refreshes the binding prior to the binding expires. The indicator
value indicates a minimum time (given in seconds), prior to the value indicates a minimum time (given in seconds), prior to the
binding expires when the UA MUST send the REGISTER request. Even if binding expires when the UA MUST send the REGISTER request. Even if
the UA is able to to send REGISTER requests using a non-push the UA is able to to send REGISTER requests using a non-push
mechanism, the UA MUST still send a REGISTER request when it receives mechanism, the UA MUST still send a REGISTER request when it receives
a push notification, following the procedures in this section. If a push notification, following the procedures in this section. If
the REGISTER response does not contain a a 'sip.pnsreg' feature- the REGISTER response does not contain a a 'sip.pnsreg' feature-
capability indicator, the UA SHOULD only send a re-registration capability indicator, the UA SHOULD only send a binding-refresh
REGISTER request when it receives a push notification (even if the UA REGISTER request when it receives a push notification (even if the UA
is able to use a non-push mechanism for sending re-registration is able to use a non-push mechanism for sending binding-refresh
REGISTER requests), or when there are circumstances (e.g., if the UA REGISTER requests), or when there are circumstances (e.g., if the UA
is assigned new contact parameters due to a network configuration is assigned new contact parameters due to a network configuration
change) that require an immediate REGISTER request to be sent. change) that require an immediate REGISTER request to be sent.
NOTE: If the UA uses a non-push mechanism to wake and send a binding NOTE: If the UA uses a non-push mechanism to wake and send a binding
refresh REGISTER request, such REGISTER request will update the refresh REGISTER request, such REGISTER request will update the
binding expiration timer, and the proxy does not need to request a binding expiration timer, and the proxy does not need to request that
push notification towards the UA in order to wake the UA. The proxy a push notification is sent to the UA in order to wake the UA. The
will still request a push notification towards the UA when the proxy proxy will still request that a push notification is sent to the UA
receives a SIP request addressed towards the UA (Section 5.3.2). when the proxy receives a SIP request addressed towards the UA
This allows the UA to e.g., use timers for sending binding-refresh (Section 5.3.2). This allows the UA to e.g., use timers for sending
REGISTER requests, but to be suspended (in order to save battery binding-refresh REGISTER requests, but to be suspended (in order to
resources etc) between sending the REGISTER requests and use push save battery resources etc) between sending the REGISTER requests and
notification to wake the UA to process incoming calls. use push notification to wake the UA to process incoming calls.
NOTE: This specification does not define any usage of a push NOTE: This specification does not define any usage of a push
notification payload. As defined in Section 5.3.2, a proxy must not notification payload. As defined in Section 5.3.2, a proxy must not
include any payload in the push notification request. If a SIP UA include any payload in the push notification request. If a SIP UA
receives a push notification that contains a payload the UA can receives a push notification that contains a payload the UA can
discard the payload, but the UA will still send a binding-refresh discard the payload, but the UA will still send a binding-refresh
REGISTER request. REGISTER request.
NOTE: If the SIP UA application wants to use push notifications for NOTE: If the SIP UA application wants to use push notifications for
other purposes than to trigger binding-refresh requests, it needs to other purposes than to trigger binding-refresh requests, it needs to
be able to distinguish between the different purposes when receiving be able to distinguish between the different purposes when receiving
push notifications. Mechanisms for doing that are outside the scope push notifications. Mechanisms for doing that are outside the scope
of this specification. of this specification.
As long as the UA wants to receive push notifications (requested by As long as the UA wants to receive push notifications (requested by
the proxy), the UA MUST include a pn-provider, pn-prid and a pn-param the proxy), the UA MUST include a pn-provider, pn-prid and a pn-param
(if required for the specific PNS provider) SIP URI parameter in each (if required for the specific PNS provider) SIP URI parameter in the
binding-refresh REGISTER request. Note that, in some cases, the PNS SIP Contact header field URI of each binding-refresh REGISTER
might update the PRID value, in which case the UA will include the request. Note that, in some cases, the PNS might update the PRID
new value in the pn-prid SIP URI parameter in the binding-refresh value, in which case the UA will include the new value in the pn-prid
REGISTER request. SIP URI parameter in the binding-refresh REGISTER request.
If the UA no longer wants to receive push notifications (requested by If the UA no longer wants to receive push notifications (requested by
the proxy), the UA MUST send a binding-refresh REGISTER request the proxy), the UA MUST send a binding-refresh REGISTER request
without including the SIP URI parameters described above, or the UA without including the SIP URI parameters described above, or the UA
MUST remove the registration. MUST remove the registration, unless the UA is no longer able to
perform SIP procedures (e.g., due to a forced shutdown).
If a UA's subscription to a PNS (and the associated PRID) is only If a UA's subscription to a PNS (and the associated PRID) is only
valid for a limited time then the UA is responsible for retrieving valid for a limited time then the UA is responsible for retrieving
new subscription details from the PNS and sending a REGISTER request new subscription details from the PNS and sending a REGISTER request
with the updated pn parameters to the proxy prior to the expiry of with the updated pn parameters to the proxy prior to the expiry of
the existing subscription. If a UA's subscription to a PNS expires the existing subscription. If a UA's subscription to a PNS expires
then the UA MUST send a REGISTER without the pn parameters (to tell then the UA MUST send a REGISTER without the pn parameters (to tell
the proxy that it no longer wants push notifications) or terminate the proxy that it no longer wants push notifications) or terminate
the registration. The exact mechanisms for expiry and renewal of the registration. The exact mechanisms for expiry and renewal of
PRIDs will be PNS-specific and are outside the scope of this PRIDs will be PNS-specific and are outside the scope of this
document. document.
For privacy and security reasons, the UA MUST NOT include the SIP URI For privacy and security reasons, the UA MUST NOT include the SIP URI
parameters defined in this document in non-REGISTER request, to parameters defined in this document in non-REGISTER request, to
prevent the PNS information associated with the UA from reaching the prevent the PNS information associated with the UA from reaching the
remote peer. For example, the UA MUST NOT include the SIP URI remote peer. For example, the UA MUST NOT include the SIP URI
parameters in the Contact header field of an INVITE request. parameters in the Contact header field of an INVITE request.
REGISTER requests will not reach the remote peer, as they will be
terminated by the registrar of the UA. However, the registrar MUST
still ensure that the parameters are not sent to other users, e.g.,
using the SIP event package for registrationss mechanism [RFC3680].
See Section 13 for more information.
4.2. Query Network Push Notification Capabilities 4.2. Query Network Push Notification Capabilities
A SIP UA might need to query the SIP network for push notification A SIP UA might need to query the SIP network for push notification
capabilities (e.g., related to VAPID) before it registers with the capabilities (e.g., related to VAPID) before it registers with the
PNS, and before it indicates that it wants to receive push PNS, and before it indicates that it wants to receive push
notifications. The UA can do so by only including the pn-provider notifications. The UA can do so by only including the pn-provider
SIP URI parameter in the SIP Contact header field URI of the REGISTER SIP URI parameter in the SIP Contact header field URI of the REGISTER
request, but without including the pn-prid SIP URI parameter. Later, request, but without including the pn-prid SIP URI parameter. Later,
once the UA has received a response to the REGISTER request with the once the UA has received a response to the REGISTER request with the
skipping to change at page 10, line 31 skipping to change at page 11, line 17
5.1. PNS Provider 5.1. PNS Provider
The type of PNS is identified by the pn-provider SIP URI parameter. The type of PNS is identified by the pn-provider SIP URI parameter.
The protocol and format used for the push notification requests are The protocol and format used for the push notification requests are
PNS-specific, and the details for constructing and sending a push PNS-specific, and the details for constructing and sending a push
notification request are outside the scope of this specification. notification request are outside the scope of this specification.
5.2. Trigger Periodic Binding Refresh 5.2. Trigger Periodic Binding Refresh
In order to request push notifications towards a SIP UA that will In order to request that a push notification is sent to a SIP UA that
trigger the UA to send binding-refresh SIP REGISTER requests, the SIP will trigger the UA to send binding-refresh SIP REGISTER requests,
proxy needs to have information about when a registration will the SIP proxy needs to have information about when a registration
expire. The proxy needs to be able to retrieve the information from will expire. The proxy needs to be able to retrieve the information
the registrar using some mechanism. Such mechanisms are outside the from the registrar using some mechanism, or run its own registration
scope of this document, but could be implemented e.g., using the timers. Such mechanisms are outside the scope of this document, but
SIPregistration event package mechanism [RFC3680]. could be implemented e.g., using the SIP event package for
registrations mechanism [RFC3680].
When the proxy receives an indication that the UA needs to send a When the proxy receives an indication that the UA needs to send a
binding-refresh REGISTER request, the proxy requests a push binding-refresh REGISTER request, the proxy request that a push
notification towards the UA. notification is sent to the UA.
Note that the push notification needs to be requested early enough Note that the push notification needs to be requested early enough
for the associated binding-refresh REGISTER request to reach the for the associated binding-refresh REGISTER request to reach the
registrar before the registration expires. It is RECOMMENDED that registrar before the registration expires. It is RECOMMENDED that
the proxy requests the push notification at least 120 seconds before the proxy requests the push notification at least 120 seconds before
the registration expires. the registration expires.
If the UA has indicated, using the 'sip.pnsreg' media feature tag, If the UA has indicated, using the 'sip.pnsreg' media feature tag,
that it is able to wake using a non-push mechanism for sending that it is able to wake using a non-push mechanism for sending
binding-refresh REGISTER requests, if the proxy does not receive a binding-refresh REGISTER requests, if the proxy does not receive a
REGISTER request prior to 120 seconds before the registration REGISTER request prior to 120 seconds before the registration
expires, the proxy MAY request a push notification towards the UA, to expires, the proxy MAY request that a push notification is sent to
trigger the UA to send a REGISTER request. the UA, to trigger the UA to send a REGISTER request.
NOTE: As described in Section 4.2, a SIP UA might send a REGISTER NOTE: As described in Section 4.2, a SIP UA might send a REGISTER
request without including a pn-prid SIP URI parameter, in order to request without including a pn-prid SIP URI parameter, in order to
retrieve push notification capabilities from the network before the retrieve push notification capabilities from the network before the
UA expects to receive push notifications from the network. A proxy UA expects to receive push notifications from the network. A proxy
will not request push notifications towards a UA that has not will not request that push notifications are sent to a UA that has
provided a pn-prid SIP URI parameter. not provided a pn-prid SIP URI parameter (Section 5.3.2).
If the proxy receives information that a registration has expired, If the proxy receives information that a registration has expired,
the proxy MUST NOT request further push notifications towards the UA. the proxy MUST NOT request that further push notifications are sent
to the UA.
5.3. SIP Requests 5.3. SIP Requests
5.3.1. REGISTER 5.3.1. REGISTER
The procedures in this section apply when the SIP proxy receives a The procedures in this section apply when the SIP proxy receives a
SIP REGISTER request (initial REGISTER request for a registration, or SIP REGISTER request (initial REGISTER request for a registration, or
a binding-refresh REGISTER request) that contains a pn-provider SIP a binding-refresh REGISTER request) that contains a pn-provider SIP
URI parameter identifying a type of PNS. If the proxy receives a URI parameter identifying a type of PNS. If the proxy receives a
REGISTER request that does not contain a pn-provider SIP URI REGISTER request that does not contain a pn-provider SIP URI
parameter, or that removes the registration, the proxy MUST NOT parameter, or that removes the registration, the proxy MUST NOT
request push notifications towards the UA associated with the request that a push notification is sent to the UA associated with
REGISTER request or perform any other procedures in this section. the REGISTER request or perform any other procedures in this section.
As described in Section 4.2, a SIP UA might send a REGISTER request As described in Section 4.2, a SIP UA might send a REGISTER request
without including a pn-prid SIP URI parameter in the Contact header without including a pn-prid SIP URI parameter in the Contact header
field URI, in order to retrieve push notification capabilities from field URI, in order to retrieve push notification capabilities from
the network before the UA the proxy will request push notifications the network before the UA the proxy will request that a push
towards the UA. The procedures in this section apply to both the notification is sent to the UA. The procedures in this section apply
case when the REGISTER request contains a pn-prid SIP URI parameter, to both the case when the REGISTER request contains a pn-prid SIP URI
and when it does not. parameter, and when it does not.
When the proxy receives a REGISTER request, if the REGISTER request When the proxy receives a REGISTER request, if the REGISTER request
contains a Feature-Caps header field with a 'sip.pns' feature- contains a Feature-Caps header field with a 'sip.pns' feature-
capability indicator, it indicates that a proxy between this proxy capability indicator, it indicates that a proxy between this proxy
and the UA supports requesting push notifications towards the UA. and the UA supports requesting that push notifications are sent to
The proxy MUST skip the rest of the procedures in this section, and the UA. The proxy MUST skip the rest of the procedures in this
process the REGISTER request using normal SIP procedures. section, and process the REGISTER request using normal SIP
procedures.
If the proxy considers the requested registration expiration interval If the proxy considers the requested registration expiration interval
[RFC3261] to be too short, the proxy MUST either send a 423 (Interval [RFC3261] to be too short, the proxy MUST either send a 423 (Interval
Too Brief) response to the REGISTER request, or skip the rest of the Too Brief) response to the REGISTER request, or skip the rest of the
procedures in this section and process the REGISTER request using procedures in this section and process the REGISTER request using
normal SIP procedures. If the proxy sends a 423 (Interval Too Brief) normal SIP procedures. If the proxy sends a 423 (Interval Too Brief)
response, the proxy SHOULD insert a Feature-Caps header field with a response, the proxy SHOULD insert a Feature-Caps header field with a
'sip.pns' feature-capability indicator in the response, identifying 'sip.pns' feature-capability indicator in the response, identifying
each type of PNS that the proxy supports. Similarly, when the proxy each type of PNS that the proxy supports. Similarly, when the proxy
receives a 2xx response to the REGISTER request (see below), if the receives a 2xx response to the REGISTER request (see below), if the
proxy considers the registration expiration interval indicated by the proxy considers the registration expiration interval indicated by the
registrar too short, the proxy MUST NOT insert a Feature-Caps header registrar too short, the proxy MUST NOT insert a Feature-Caps header
field with a 'sip.pns' feature-capability indicator in the response, field with a 'sip.pns' feature-capability indicator in the response,
and the proxy MUST NOT request push notifications associated with the and the proxy MUST NOT request push notifications associated with the
registration. A registration expiration interval MUST be considered registration.
too short if the interval is smaller than the time prior to
expiration that the proxy would request a push notification. The A registration expiration interval MUST be considered too short if
proxy MAY consider the interval too small based on its own policy so the the registration would expire before the proxy would request that
as to reduce load on the system. a push notification is sent to the UA, in order to trigger the UA to
send a REGISTER request. The proxy MAY consider the interval too
short based on its own policy so as to reduce load on the system.
Otherwise, if the pn-provider SIP URI parameter identifies a type of Otherwise, if the pn-provider SIP URI parameter identifies a type of
PNS that the proxy does not support, or if the REGISTER request does PNS that the proxy does not support, or if the REGISTER request does
not contain all additional information required for the specific type not contain all additional information required for the specific type
of PNS, the proxy MUST either forward the request (e.g., if the proxy of PNS, the proxy SHOULD send a SIP 555 (Push Notification Service
knows that another proxy that will receive the REGISTER request Not Supported) response to the REGISTER request, unless the proxy
supports the type of PNS) or send a SIP 555 (Push Notification knows (based on local configuration) that another proxy that will
Service Not Supported) response to the REGISTER request. If the receive the REGISTER request supports the type of PNS, in which case
proxy sends a SIP 555 (Push Notification Service Not Supported) it MAY forward the request. If the proxy sends a SIP 555 (Push
response Section 8.1, the proxy SHOULD insert a Feature-Caps header Notification Service Not Supported) response Section 8.1, the proxy
field with a 'sip.pns' feature-capability indicator in the response, SHOULD insert a Feature-Caps header field with a 'sip.pns' feature-
identifying the type of each PNS that the proxy supports. The capability indicator in the response, identifying the type of each
decision whether to forward the request, or to send a response, is PNS that the proxy supports. The decision whether to forward the
done based on local policy. request, or to send a response, is done based on local policy.
If the proxy supports the type of PNS identified by the pn-provider If the proxy supports the type of PNS identified by the pn-provider
SIP URI parameter, the proxy MUST insert a Feature-Caps header field SIP URI parameter, the proxy MUST insert a Feature-Caps header field
with a 'sip.pns' feature-capability indicator, identifying the type with a 'sip.pns' feature-capability indicator, identifying the type
of PNS, in the REGISTER request before forwarding the REGISTER of PNS, in the REGISTER request before forwarding the REGISTER
request towards the registrar. This will inform proxies that are not request towards the registrar. This will inform proxies that are not
between the push proxy and the UA that the proxy supports, and will between the push proxy and the UA that the proxy supports, and will
request (if the Contact header field URI of the REGISTER request request (if the Contact header field URI of the REGISTER request
contains a pn-prid SIP URI parameter), push notifications towards the contains a pn-prid SIP URI parameter), that push notifications are
UA. sent to the UA.
If the proxy inserted a Feature-Caps header field with a 'sip.pns' If the proxy inserted a Feature-Caps header field with a 'sip.pns'
feature-capability indicator in the REGISTER request (see above), if feature-capability indicator in the REGISTER request (see above), if
the proxy receives a 2xx response to the REGISTER request, the proxy the proxy receives a 2xx response to the REGISTER request, the proxy
MUST insert a Feature-Caps header field with a 'sip.pns' feature- MUST insert a Feature-Caps header field with a 'sip.pns' feature-
capability indicator in the response, identifying the type of PNS. capability indicator in the response, identifying the type of PNS.
This will inform the UA that the proxy supports, and will request (if This will inform the UA that the proxy supports, and will request (if
the Contact header field URI of the REGISTER request contained a pn- the Contact header field URI of the REGISTER request contained a pn-
prid SIP URI parameter), push notifications towards the UA. The prid SIP URI parameter), that push notifications are sent to the UA.
proxy MUST indicate support only of the same PNS that was identified The proxy MUST indicate support only of the same PNS that was
in the pn-provider SIP URI parameter in the REGISTER request. If the identified in the pn-provider SIP URI parameter in the REGISTER
proxy receives a receives a SIP 555 (Push Notification Service Not request. If the proxy receives a SIP 555 (Push Notification Service
Supported) response, the proxy SHOULD insert a Feature-Caps header Not Supported) response, the proxy SHOULD insert a Feature-Caps
field with a 'sip.pns' feature-capability indicator in the response, header field with a 'sip.pns' feature-capability indicator in the
identifying the type of each PNS that the proxy supports. response, identifying the type of each PNS that the proxy supports.
In addition, if the proxy receives a 2xx response to the REGISTER In addition, if the proxy receives a 2xx response to the REGISTER
request: request:
o if the proxy supports, and will use, the VAPID mechanism, the o if the proxy supports, and will use, the VAPID mechanism, the
proxy MUST insert a Feature-Caps header field with a 'sip.vapid' proxy MUST insert a Feature-Caps header field with a 'sip.vapid'
feature-capability indicator in the response. The header field feature-capability indicator in the response. The header field
parameter contains the public key identifying the proxy [RFC8292]. parameter contains the public key identifying the proxy [RFC8292].
The proxy MUST determine whether the PNS supports the VAPID The proxy MUST determine whether the PNS supports the VAPID
mechanism before it inserts the feature-capability indicator. mechanism before it inserts the feature-capability indicator.
o if the proxy received a 'sip.pnsreg' media feature tag in the o if the proxy received a 'sip.pnsreg' media feature tag in the
REGISTER request, the proxy SHOULD include a 'sip.pnsreg' feature- REGISTER request, the proxy SHOULD include a 'sip.pnsreg' feature-
capability indicator with an indicator value bigger than 120 in capability indicator with an indicator value bigger than 120 in
the response, unless the proxy always want to request push the response, unless the proxy always wants to request push
notifications to trigger the UA to send a REGISTER request. notifications to trigger the UA to send a REGISTER request.
5.3.2. Initial Request for Dialog or Stand-Alone Request 5.3.2. Initial Request for Dialog or Stand-Alone Request
The procedures in this section apply when the SIP proxy has indicated The procedures in this section apply when the SIP proxy has indicated
that it supports, and will request, push notifications towards the that it supports, and will request, that push notifications are sent
SIP UA. to the SIP UA.
When the proxy receives a SIP request for a new dialog (e.g., a SIP When the proxy receives a SIP request for a new dialog (e.g., a SIP
INVITE request) or a stand-alone SIP request (e.g., a SIP MESSAGE INVITE request) or a stand-alone SIP request (e.g., a SIP MESSAGE
request) addressed towards a SIP UA, if the Request-URI of the request) addressed towards a SIP UA, if the Request-URI of the
request contains a pn-provider, a pn-prid and a pn-param (if required request contains a pn-provider, a pn-prid and a pn-param (if required
for the specific PNS provider) SIP URI parameter, the proxy requests for the specific PNS provider) SIP URI parameter, the proxy requests
a push notification towards the UA, using the PRID included in the that a push notification is sent to the UA, using the PRID included
pn-prid SIP URI parameter and the PNS identified by the pn-provider in the pn-prid SIP URI parameter and the PNS identified by the pn-
SIP URI parameter. provider SIP URI parameter.
The push notification will trigger the UA to send a binding-refresh The push notification will trigger the UA to send a binding-refresh
REGISTER request. The proxy will process the REGISTER request and REGISTER request. The proxy will process the REGISTER request and
the associated response as described in Section 5.3.1. In case of a the associated response as described in Section 5.3.1. In case of a
2xx response to the REGISTER request, once the proxy has forwarded 2xx response to the REGISTER request, once the proxy has forwarded
the REGISTER response towards the UA, if the contact of the SIP the REGISTER response towards the UA, if the contact of the SIP
REGISTER request associated with the REGISTER response matches the REGISTER request associated with the REGISTER response matches the
Request-URI of the SIP request to be forwarded, and the contact was Request-URI of the SIP request to be forwarded, and the contact was
also present (and has not expired) in the REGISTER response, the also present (and has not expired) in the REGISTER response, the
proxy can forward the SIP request towards the UA, using normal SIP proxy can forward the SIP request towards the UA, using normal SIP
procedures. If the contact of the REGISTER request does not match procedures. If the contact of the REGISTER request does not match
the Request-URI of the SIP request to be forwarded, or if the contact the Request-URI of the SIP request to be forwarded, or if the contact
was not present in the REGISTER response, the proxy MUST reject the was not present in the REGISTER response, the proxy MUST reject the
SIP request with a 404 (Not Found) response. This can happen if the SIP request. It is RECOMMENDED that the proxy sends either a 404
UA sends a binding-refresh REGISTER request that does not contain the (Not Found) response or a 480 (Temporarily Unavailable) response, but
other response codes can be used as well. This can happen if the UA
sends a binding-refresh REGISTER request that does not contain the
previously registered contact at the same time the registrar forwards previously registered contact at the same time the registrar forwards
a SIP request towards a UA using the previously registered contact in a SIP request towards a UA using the previously registered contact in
the Request-URI. the Request-URI.
NOTE: If the SIP request does not contain the pn- parameters, the NOTE: If the SIP request does not contain the pn- parameters, the
proxy processing of the request is based on local policy, e.g., proxy processing of the request is based on local policy, e.g.,
depending on whether the proxy servers requests towards UAs that do depending on whether the proxy servers requests towards UAs that do
not use the SIP push mechanism, in which case the proxy will forward not use the SIP push mechanism, in which case the proxy will forward
the request using normal SIP procedures. Otherwise the proxy might the request using normal SIP procedures. Otherwise the proxy might
reject the request. reject the request.
When matching the Request-URI of the SIP request to be forwarded with When matching the Request-URI of the SIP request to be forwarded with
a contact of a REGISTER request, the proxy uses the URI comparison a contact of a REGISTER request, the proxy uses the URI comparison
rules in [RFC8292], with the following addition: the pn-prid SIP URI rules in [RFC8292], with the following addition: the pn-prid SIP URI
parameter MUST also match. If the parameter is not present in the parameter MUST also match. If the parameter is not present in the
Request-URI of the SIP request, or in the contact of the REGISTER, Request-URI of the SIP request, or in the contact of the REGISTER,
there is no match. there is no match.
The reason the proxy needs to wait for the REGISTER response before The reason the proxy needs to wait for the REGISTER response before
forwarding the SIP request is to make sure that the REGISTER request forwarding the SIP request is to make sure that the REGISTER request
has been accepted by the registrar, and that the UA which initiated has been accepted by the registrar, and that the UA that initiated
the REGISTER request is authorized to receive messages for the the REGISTER request is authorized to receive messages for the
Request-URI. However, if the proxy is able to authorize the sender Request-URI. However, if the proxy is able to authorize the sender
of the REGISTER request, it does not need to wait for the associated of the REGISTER request, it does not need to wait for the associated
2xx response before it forwards the SIP request towards the UA. The 2xx response before it forwards the SIP request towards the UA. The
mechanism for authorizing the UA is outside the scope of this mechanism for authorizing the UA is outside the scope of this
document. document.
As both the SIP request to be forwarded towards the UA and the As both the SIP request to be forwarded towards the UA and the
binding-refresh REGISTER request triggered by the push notification binding-refresh REGISTER request triggered by the push notification
request will convey pn- SIP URI parameters associated with the SIP request will convey pn- SIP URI parameters associated with the SIP
registration, those can be used to match the SIP request with the registration, those can be used to match the SIP request with the
binding-refresh REGISTER request (even if other parts of the most binding-refresh REGISTER request (even if other parts of the most
recent contact and the Request-URI of the SIP request do not match). recent contact and the Request-URI of the SIP request do not match).
NOTE: The proxy needs to store (or be able to retrieve) the contact NOTE: The proxy needs to store (or be able to retrieve) the contact
of the most recent REGISTER 2xx response, to be able to compare it of the most recent REGISTER 2xx response, to be able to compare it
with the Request-URI of the request to be forwarded towards the UA. with the Request-URI of the request to be forwarded towards the UA.
In case of non-2xx response to the REGISTER request, the proxy MUST In case of non-2xx response to the REGISTER request, the proxy MUST
reject the SIP request with a 404 (Not Found) response. reject the SIP request.It is RECOMMENDED that the proxy sends either
a 404 (Not Found) response or a 480 (Temporarily Unavailable)
response, but other response codes can be used as well.
If the push notification request fails (see PNS-specific If the push notification request fails (see PNS-specific
documentation for details), the proxy MUST reject the SIP request documentation for details), the proxy MUST reject the SIP request.
with a 480 (Temporarily Unavailable) response. It is RECOMMENDED that the proxy sends either a 404 (Not Found)
response or a 480 (Temporarily Unavailable) response, but other
response codes can be used as well.
If the proxy does not receive the REGISTER request from the UA within If the proxy does not receive the REGISTER request from the UA within
a given time after the proxy has requested the push notification, the a given time after the proxy has requested the push notification, the
proxy MUST reject the request with a 480 (Temporarily Unavailable) proxy MUST reject the request with a 480 (Temporarily Unavailable)
response. The time value is set based on local policy. response. The time value is set based on local policy.
As dicussed in [RFC4320] and [RFC4321], non-INVITE transactions must As discussed in [RFC4320] and [RFC4321], non-INVITE transactions must
complete immediately or risk losing a race that results in stress on complete immediately or risk losing a race that results in stress on
intermediaries and state misalignment at the endpoints. The intermediaries and state misalignment at the endpoints. The
mechanism defined in this document inherently delays the final mechanism defined in this document inherently delays the final
response to any non-INVITE request that requires a push notification. response to any non-INVITE request that requires a push notification.
In particular, while waiting for the push notification request to In particular, while waiting for the push notification request to
succeed, and the associated REGISTER request to arrive from the SIP succeed, and the associated REGISTER request to arrive from the SIP
UA, the proxy needs to take into consideration that the transaction UA, the proxy needs to take into consideration that the transaction
associated with the SIP request will eventually time out at the associated with the SIP request will eventually time out at the
sender of the request (UAC), and the sender will consider the sender of the request (UAC), and the sender will consider the
transaction a failure. If the proxy forwards the SIP request towards transaction a failure. If the proxy forwards the SIP request towards
skipping to change at page 15, line 47 skipping to change at page 16, line 45
REGISTER request, from when the proxy has requested a push REGISTER request, from when the proxy has requested a push
notification, is typically around 2 seconds. However, the time might notification, is typically around 2 seconds. However, the time might
vary depending on the characteristics and load of the SIP network and vary depending on the characteristics and load of the SIP network and
the PNS. the PNS.
The proxy MUST NOT include the SIP request as payload in the The proxy MUST NOT include the SIP request as payload in the
requested push message. requested push message.
If the proxy has knowledge that the UA is awake, and that the UA is If the proxy has knowledge that the UA is awake, and that the UA is
able to receive the SIP request without first sending a REGISTER able to receive the SIP request without first sending a REGISTER
request, the proxy MAY choose to not request a push notification request, the proxy MAY choose to not request that a push notification
towards the UA (and wait for the associated REGISTER request and 2xx is sent to the UA (and wait for the associated REGISTER request and
response) before it tries to forward the SIP request towards the UA. 2xx response) before it tries to forward the SIP request towards the
The mechanisms for getting such knowledge might be dependent on UA. The mechanisms for getting such knowledge might be dependent on
implementation or deployment architecture, and are outside the scope implementation or deployment architecture, and are outside the scope
of this document. Similarly, if the Request-URI of the SIP request of this document. Similarly, if the Request-URI of the SIP request
only contains any pn-provider SIP URI parameter, but no other pn- SIP only contains any pn-provider SIP URI parameter, but no other pn- SIP
URI parameters, e.g., because the SIP UA has not included them in a URI parameters, e.g., because the SIP UA has not included them in a
REGISTER request (Section 4.2), the proxy is not able to request a REGISTER request (Section 4.2), the proxy is not able to request that
push notification towards the UA. If the proxy has knowledge that a push notification is sent to the UA. If the proxy has knowledge
the UA is awake, and that the UA is able to receive the SIP request, that the UA is awake, and that the UA is able to receive the SIP
the proxy MAY forwards the request towards the UA. Otherwise the request, the proxy MAY forwards the request towards the UA.
proxy MUST reject the SIP request with a 480 (Temporarily Otherwise the proxy MUST reject the SIP request with a 480
Unavailable) response. (Temporarily Unavailable) response.
6. Support Of Longlived SIP Dialogs 6. Support Of Longlived SIP Dialogs
Some SIP dialogs might have a long lifetime, with little activity. Some SIP dialogs might have a long lifetime, with little activity.
For example, when the SIP event notification mechanism [RFC6665] is For example, when the SIP event notification mechanism [RFC6665] is
used, there might be a long period between mid-dialog requests are used, there might be a long period between mid-dialog requests are
sent. Because of this a SIP UA might get suspended, and needs to be sent. Because of this a SIP UA might get suspended, and needs to be
awaken in order to be able to receive mid-dialog requests. awaken in order to be able to receive mid-dialog requests.
When the proxy receives a SIP request for a new dialog, or a stand- When the proxy receives a SIP request for a new dialog, or a stand-
alone SIP request, addressed towards a UA, the request will contain alone SIP request, addressed towards a UA, the request will contain
information (pn- SIP URI parameters) that allows proxy to request information (pn- SIP URI parameters) that allows proxy to request
push notifications towards the UA Section 5.3.2. However, this that a push notification is sent to the UA Section 5.3.2. However,
information will not be present in mid-dialog requests towards the this information will not be present in mid-dialog requests towards
UA. Instead, the proxy need to support a mechanism where it stores the UA. Instead, the proxy need to support a mechanism where it
the information needed to request a push notification towards the UA stores the information needed to request that a push notification is
and be able to find and retrieve that information when it receives a sent to the UA and be able to find and retrieve that information when
mid-dialog request. This section defines such mechanism. The UA and it receives a mid-dialog request. This section defines such
proxy procedures in this section are applied in addition to the mechanism. The UA and proxy procedures in this section are applied
generic procedures defined in this specification. in addition to the generic procedures defined in this specification.
+--------+ +---------+ +-----------+ +-------------+
| | | | | | | SIP |
| SIP UA | | Push | | SIP Proxy | | Registrar / |
| | | Service | | | | Home Proxy |
+--------+ +---------+ +-----------+ +-------------+
| | | |
| Subscribe | | |
|---------------->| | |
| | | |
| PRID | | |
|<----------------| | |
| | | |
| SIP REGISTER (PRID) | |
|===================================>| |
| | |SIP REGISTER (PRID)|
| | |==================>|
| | | |
| | +-----------------------+ |
| | | Store PRID (key=PURR) | |
| | +-----------------------+ |
| | | |
| | | SIP 200 OK |
| | |<==================|
| SIP 200 OK (PURR) | |
|<===================================| |
| | | |
| | | |
| SIP INVITE (PURR) | |
|===================================>| |
| | |SIP INVITE (PURR) |
| | |==================>|
| | | |
| | | SIP 200 OK |
| | |<==================|
| SIP 200 OK | | |
|<===================================| |
| | | |
| | | |
| | | |
| | |SIP UPDATE (PURR) |
| | |<==================|
| | | |
| | +-----------------------+ |
| | | Fetch PRID (key=PURR) | |
| | +-----------------------+ |
| | | |
| |Push Request (PRID) |
| |<-----------------| |
|Push Message (PRID) | |
|<----------------| | |
| | | |
| SIP REGISTER (PRID) | |
|===================================>| |
| | |SIP REGISTER (PRID)|
| | |==================>|
| | | |
| | | SIP 200 OK |
| | |<==================|
| SIP 200 OK | | |
|<===================================| |
| | | |
| SIP UPDATE | | |
|<===================================| |
| | | |
------- Push Notification API
======= SIP
Figure 3: SIP Push Longlived Dialog Flow
6.1. SIP UA Behavior 6.1. SIP UA Behavior
6.1.1. Initial Request for Dialog 6.1.1. Initial Request for Dialog
When the UA sends in initial request for a dialog, or a 2xx response When the UA sends an initial request for a dialog, or a 2xx response
to such requests, if the UA is willing to receive push notifications to such requests, if the UA is willing to receive push notifications
triggered by incoming mid-dialog requests, the UA MUST include a 'pn- triggered by incoming mid-dialog requests, the UA MUST include a 'pn-
purr' SIP URI parameter in the Contact header of the request or purr' SIP URI parameter in the Contact header field of the request or
response. The UA MUST include a parameter value identical to the the response. The UA MUST include a parameter value identical to the the
last 'sip.pnspurr' feature-capability indicator that it received in a last 'sip.pnspurr' feature-capability indicator that it received in a
REGISTER response. REGISTER response (Section 6.2.1).
The UA decision whether it is willing to receive push notifications The UA decision whether it is willing to receive push notifications
triggered by incoming mid-dialog requests is done based on local triggered by incoming mid-dialog requests is done based on local
policy. Such policy might be based on the type of SIP dialog, the policy. Such policy might be based on the type of SIP dialog, the
type of media (if any) negotiated for the dialog [RFC3264], etc. type of media (if any) negotiated for the dialog [RFC3264], etc.
NOTE: As the 'pn-purr' SIP URI parameter only applies to a give NOTE: As the 'pn-purr' SIP URI parameter only applies to a given
dialog, the UA needs to include a 'pn-purr' parameter in the Contact dialog, the UA needs to include a 'pn-purr' parameter in the Contact
header of the request or response for each dialog in which the UA is header field of the request or response for each dialog in which the
willing to receive push notifications triggered by incoming mid- UA is willing to receive push notifications triggered by incoming
dialog requests. mid-dialog requests.
6.2. SIP Proxy Behavior 6.2. SIP Proxy Behavior
6.2.1. REGISTER 6.2.1. REGISTER
When the proxy receives an initial REGISTER request for a When the proxy receives an initial REGISTER request for a
registration from the UA, if the proxy supports requesting push registration from the UA, if the proxy supports requesting that push
notifications, triggered by mid-dialog requests, towards the notifications triggered by mid-dialog requests are sent to the
registered UA, the proxy MUST store the information (the pn- SIP URI registered UA, the proxy MUST store the information (the pn- SIP URI
parameters) needed to request push notifications associated with the parameters) needed to request that push notifications associated with
registration towards the UA. In addition the proxy MUST generate a the registration are sent to the UA. In addition the proxy MUST
unique (within the context of the proxy) value, referred to as the generate a unique (within the context of the proxy) value, referred
PURR (Proxy Unique Registration Reference), that is unique within the to as the PURR (Proxy Unique Registration Reference), that is unique
context of the proxy and that can be used as a key to retrieve the within the context of the proxy and that can be used as a key to
information. When the proxy receives the associated 2xx REGISTER retrieve the information. When the proxy receives the associated 2xx
response, it adds a 'sip.pnspurr' feature-capability indicator with REGISTER response, it adds a 'sip.pnspurr' feature-capability
the PURR value to the associated 2xx REGISTER response. When the indicator with the PURR value to the associated 2xx REGISTER
proxy receives a binding-refresh REGISTER request, it MUST add a response. When the proxy receives a binding-refresh REGISTER
'sip.pnspurr' feature-capability indicator with the previously request, it MUST add a 'sip.pnspurr' feature-capability indicator
generated key as the value to the associated 2xx REGISTER response. with the previously generated key as the value to the associated 2xx
REGISTER response.
The PURR value MUST be generated in such a way so that it cannot be The PURR value MUST be generated in such a way so that it cannot be
used to retrieve information about the user or associate it with used to retrieve information about the user or associate it with
registrations. It can be generated e.g., by utilizing a registrations. It can be generated e.g., by utilizing a
cryptographically secure random function. cryptographically secure random function.
In order to prevent client fingerprinting, the proxy MUST In order to prevent client fingerprinting, the proxy MUST
periodically generate a new PURR value (even if pn- parameters did periodically generate a new PURR value (even if pn- parameters did
not change) and provide the new value to the UA in a 2xx binding- not change) and provide the new value to the UA in a 2xx binding-
refresh REGISTER response. However, as long as there are ongoing refresh REGISTER response. However, as long as there are ongoing
dialogs associated with the old value, the proxy MUST store it so dialogs associated with the old value, the proxy MUST store it so
that it can request push notifications towards the UA when it that it can request that push notifications are sent to the UA when
receives a mid-dialog request addressed towards the UA. it receives a mid-dialog request addressed towards the UA.
6.2.2. Initial Request for Dialog 6.2.2. Initial Request for Dialog
When the proxy receives an initial request for a dialog from the UA, When the proxy receives an initial request for a dialog from the UA,
and if the request contains a 'pn-purr' SIP URI parameter in the and if the request contains a 'pn-purr' SIP URI parameter in the
Contact header field with a PURR value that the proxy has generated Contact header field with a PURR value that the proxy has generated
Section 6.2.2, the proxy MUST add a Record-Route header to the (Section 6.2.2), the proxy MUST add a Record-Route header to the
request, to insert itself in the dialog route [RFC3261]. request, to insert itself in the dialog route [RFC3261].
When the proxy receives an initial request for a dialog addressed When the proxy receives an initial request for a dialog addressed
towards the UA, and if the proxy has generated a PURR value towards the UA, and if the proxy has generated a PURR value
associated with the pn- parameters included in the SIP-URI of the associated with the pn- parameters included in the SIP-URI of the
request Section 6.2.2, the proxy MUST add a Record-Route header to request Section 6.2.2, the proxy MUST add a Record-Route header to
the request, to insert itself in the dialog route [RFC3261]. the request, to insert itself in the dialog route [RFC3261].
6.2.3. Mid-Dialog Request 6.2.3. Mid-Dialog Request
When the proxy receives a mid-dialog request addressed towards the When the proxy receives a mid-dialog request addressed towards the
UA, if the request contains a 'pn-purr' SIP URI parameter and if the UA, if the request contains a 'pn-purr' SIP URI parameter and if the
proxy is able to retrieve the stored information needed to request a proxy is able to retrieve the stored information needed to request
push notification towards the UA (Section 6.2.1), the proxy MUST that a push notification is sent the UA (Section 6.2.1), the proxy
request a push notification towards the UA. Once the proxy has MUST request that a push notification is sent to the UA. Once the
received the triggered REGISTER request, and the associated proxy has received the triggered REGISTER request, and the associated
successful response, the proxy can forward the mid-dialog request successful response, the proxy can forward the mid-dialog request
towards the UA. towards the UA.
As described in Section 5.3.2, while waiting for the push As described in Section 5.3.2, while waiting for the push
notification request to succeed, and the associated REGISTER request notification request to succeed, and the associated REGISTER request
to arrive from the SIP UA, the proxy needs to take into consideration to arrive from the SIP UA, the proxy needs to take into consideration
that the transaction associated with the NOTIFY request will that the transaction associated with the NOTIFY request will
eventually time out at the sender of the request (UAC), and the eventually time out at the sender of the request (UAC), and the
sender will consider the transaction a failure. sender will consider the transaction a failure.
When the proxy rejects a mid-dialog request, it needs to select a
response code that only impacts the transaction associated with the
request. See [RFC5079] for more information.
7. Support Of SIP Replaces 7. Support Of SIP Replaces
[RFC3891] defines a mechanism that allows a SIP UA to replace a [RFC3891] defines a mechanism that allows a SIP UA to replace a
dialog with another dialog. A UA that wants to replace a dialog with dialog with another dialog. A UA that wants to replace a dialog with
another one will send an initial request for the new dialog. The another one will send an initial request for the new dialog. The
Request-URI of the request will contain Contact header field URI of Request-URI of the request will contain Contact header field URI of
the peer. the peer.
If the SIP Proxy wants to be able to request push notifications If the SIP Proxy wants to be able to request that a push notification
towards a UA when it receives an initial request for a dialog that is sent to a UA when it receives an initial request for a dialog that
replaces an existing dialog, using the mechanism in [RFC3891], the replaces an existing dialog, using the mechanism in [RFC3891], the
following apply: following apply:
o The proxy MUST provide a PURR to the UA during registration o The proxy MUST provide a PURR to the UA during registration
Section 6.2.1. Section 6.2.1.
o The UA MUST include a 'pn-purr' SIP URI parameter in the Contact o The UA MUST include a 'pn-purr' SIP URI parameter in the Contact
header of initial request for a dialog, or a 2xx response to such header field of the initial request for a dialog, or a 2xx
requests Section 6.1.1. This includes dialogs replacing other response to such requests Section 6.1.1. This includes dialogs
dialogs, as those dialogs might also get replaced. replacing other dialogs, as those dialogs might also get replaced.
o The proxy MUST apply the mechanism defined in Section 6.2.3 for o The proxy MUST apply the mechanism defined in Section 6.2.3 for
the initial request, and use the 'pn-purr' SIP URI parameter to the initial request, and use the 'pn-purr' SIP URI parameter to
retrieve the stored information needed to request a push retrieve the stored information needed to request that a push
notification towards the UA. notification is sent to the UA.
In addition, the operator needs to make sure that initial request for In addition, the operator needs to make sure that the initial request
dialogs, addressed towards the UA using the contact of the replaced for dialogs, addressed towards the UA using the contact of the
dialog, will be routed to the SIP proxy (in order to request push replaced dialog, will be routed to the SIP proxy (in order to request
notifications towards the UA). The procedures for doing that are that a push notification is sent to the UA). The procedures for
operator specific, and are outside the scope of this specification. doing that are operator specific, and are outside the scope of this
specification.
8. Grammar 8. Grammar
8.1. 555 (Push Notification Service Not Supported) Response Code 8.1. 555 (Push Notification Service Not Supported) Response Code
The 555 response code is added to the "Server-Error" Status-Code The 555 response code is added to the "Server-Error" Status-Code
definition. 555 (Push Notification Service Not Supported) is used to definition. 555 (Push Notification Service Not Supported) is used to
indicate that the server did not support the push notification indicate that the server did not support the push notification
service identified in a 'pn-provider' SIP URI parameter. service identified in a 'pn-provider' SIP URI parameter.
skipping to change at page 19, line 49 skipping to change at page 22, line 25
pns = tag-value pns = tag-value
tag-value = <tag-value defined in [RFC3840]> tag-value = <tag-value defined in [RFC3840]>
8.3. sip.vapid Feature-Capability Indicator 8.3. sip.vapid Feature-Capability Indicator
The sip.vapid feature-capability indicator, when included in a SIP The sip.vapid feature-capability indicator, when included in a SIP
2xx response to a SIP REGISTER request, indicates that the entity 2xx response to a SIP REGISTER request, indicates that the entity
associated with the indicator supports, and will use, the Voluntary associated with the indicator supports, and will use, the Voluntary
Application Server Identification (VAPID) [RFC8292] mechanism when Application Server Identification (VAPID) [RFC8292] mechanism when
requesting push notifications towards the SIP UA associated with the requesting that a push notification is sent to the SIP UA associated
SIP registration. The indicator value is a public key identifying with the SIP registration. The indicator value is a public key
the entity, that can be used by a SIP UA to restrict subscriptions to identifying the entity, that can be used by a SIP UA to restrict
that entity. subscriptions to that entity.
vapid-fc = "+sip.vapid" EQUAL LDQUOT vapid RDQUOT vapid-fc = "+sip.vapid" EQUAL LDQUOT vapid RDQUOT
vapid = tag-value vapid = tag-value
tag-value = <tag-value defined in [RFC3840]> tag-value = <tag-value defined in [RFC3840]>
8.4. sip.pnsreg Feature-Capability Indicator 8.4. sip.pnsreg Feature-Capability Indicator
The sip.pnsreg feature-capability indicator, when included in a SIP The sip.pnsreg feature-capability indicator, when included in a SIP
2xx response to a SIP REGISTER request, indicates that the entity 2xx response to a SIP REGISTER request, indicates that the entity
associated with the indicator expects to receive binding-refresh associated with the indicator expects to receive binding-refresh
REGISTER requests from the SIP UA associated with the registration REGISTER requests from the SIP UA associated with the registration
before the registration expires, without the entity having to request before the registration expires, without the entity having to request
push notifications towards the SIP UA in order to trigger the that a push notification is sent to the SIP UA in order to trigger
REGISTER requests. The indicator value is the minimum value (given the REGISTER requests. The indicator value is the minimum value
in seconds) before the registration expiration when the entity (given in seconds) before the registration expiration when the entity
expects to receive the REGISTER request. expects to receive the REGISTER request.
pns-fc = "+sip.pnsreg" EQUAL LDQUOT reg RDQUOT pns-fc = "+sip.pnsreg" EQUAL LDQUOT reg RDQUOT
reg = 1*DIGIT reg = 1*DIGIT
DIGIT = <DIGIT defined in [RFC3261]> DIGIT = <DIGIT defined in [RFC3261]>
8.5. sip.pnsreg Media Feature Tag 8.5. sip.pnsreg Media Feature Tag
The sip.pnsreg media feature tag, when included in the SIP Contact The sip.pnsreg media feature tag, when included in the SIP Contact
skipping to change at page 21, line 31 skipping to change at page 24, line 13
for "uri-parameter" as defined in [RFC3261]. The ABNF is as follows: for "uri-parameter" as defined in [RFC3261]. The ABNF is as follows:
uri-parameter =/ pn-provider / pn-param / pn-prid / pn-purr uri-parameter =/ pn-provider / pn-param / pn-prid / pn-purr
pn-provider = "pn-provider" EQUAL pvalue pn-provider = "pn-provider" EQUAL pvalue
pn-param = "pn-param" EQUAL pvalue pn-param = "pn-param" EQUAL pvalue
pn-prid = "pn-prid" EQUAL pvalue pn-prid = "pn-prid" EQUAL pvalue
pn-purr = "pn-purr" EQUAL pvalue pn-purr = "pn-purr" EQUAL pvalue
pvalue = <pvalue defined in [RFC3261]> pvalue = <pvalue defined in [RFC3261]>
EQUAL = <EQUAL defined in [RFC3261]> EQUAL = <EQUAL defined in [RFC3261]>
COLON = <COLON defined in [RFC3261]>
The format and semantics of pn-prid and pn-param are The format and semantics of pn-prid and pn-param are
specific to the pn-provider value. specific to the pn-provider value.
Parameter value characters that are not part of pvalue needs to be Parameter value characters that are not part of pvalue need to be
escaped, as defined in RFC 3261. escaped, as defined in RFC 3261.
9. PNS Registration Requirements 9. PNS Registration Requirements
When a new value is registered to the PNS Sub-registry, a reference When a new value is registered to the PNS Sub-registry, a reference
to a specification which describes the usage of the PNS associated to a specification that describes the usage of the PNS associated
with the value is provided. That specification MUST contain the with the value is provided. That specification MUST contain the
following information: following information:
o The value of the pn-provider SIP URI parameter. o The value of the pn-provider SIP URI parameter.
o How the pn-prid SIP URI parameter value is retrieved and set by o How the pn-prid SIP URI parameter value is retrieved and set by
the SIP UA. the SIP UA.
o How the pn-param SIP URI parameter (if required for the specific o How the pn-param SIP URI parameter (if required for the specific
PNS provider) value is retrieved and set by the SIP UA. PNS provider) value is retrieved and set by the SIP UA.
10. pn-provider, pn-param and pn-prid URI Parameters for Apple Push 10. pn-provider, pn-param and pn-prid URI Parameters for Apple Push
Notification service Notification service
When the Apple Push Notification service (APNs) is used, the PNS- When the Apple Push Notification service (APNs) is used, the PNS-
related SIP URI parameters are set as described below. related SIP URI parameters are set as described below.
skipping to change at page 22, line 16 skipping to change at page 24, line 39
the SIP UA. the SIP UA.
o How the pn-param SIP URI parameter (if required for the specific o How the pn-param SIP URI parameter (if required for the specific
PNS provider) value is retrieved and set by the SIP UA. PNS provider) value is retrieved and set by the SIP UA.
10. pn-provider, pn-param and pn-prid URI Parameters for Apple Push 10. pn-provider, pn-param and pn-prid URI Parameters for Apple Push
Notification service Notification service
When the Apple Push Notification service (APNs) is used, the PNS- When the Apple Push Notification service (APNs) is used, the PNS-
related SIP URI parameters are set as described below. related SIP URI parameters are set as described below.
For detailed information about the parameter values:
https://developer.apple.com/library/archive/documentation/NetworkingI
nternet/Conceptual/RemoteNotificationsPG/CommunicatingwithAPNs.html
[pns-apns])
The value of the pn-provider URI parameter is "apns". The value of the pn-provider URI parameter is "apns".
Example: pn-provider = apns Example: pn-provider=apns
The value of the pn-param URI parameter is a string that is composed The value of the pn-param URI parameter is a string that is composed
by two values, separated by a period (.): Team ID and Topic. The by two values, separated by a period (.): Team ID and Topic. The
Team ID is provided by Apple and is unique to a development team. Team ID is provided by Apple and is unique to a development team.
The Topic consists of the Bundle ID, which uniquelly identifies an
appliciation, and a service value that identifies a service The Topic consists of the Bundle ID, which uniquely identifies an
associated with the application, separated by a period (.). For VoIP application, and a service value that identifies a service associated
with the application, separated by a period (.). For VoIP
applications the service value is "voip". applications the service value is "voip".
Example: pn-param = DEF123GHIJ.com.yourcompany.yourexampleapp.voip Example: pn-param=DEF123GHIJ.com.example.yourexampleapp.voip
NOTE: The Bundle ID might contain one or more periods (.). Hence,
within the pn-param value, the first period will be separating the
Team ID from the Topic, and within the Topic the last period will be
separating the Bundle ID from the service.
The value of the pn-prid URI parameter is the device token, which is The value of the pn-prid URI parameter is the device token, which is
a unique identifier assigned by Apple to a specific app on a specific a unique identifier assigned by Apple to a specific app on a specific
device. device.
Example: pn-prid = 00fc13adff78512 Example: pn-prid=00fc13adff78512
For more information about the APNs Topic and device token:
https://developer.apple.com/library/archive/documentation/NetworkingI
nternet/Conceptual/RemoteNotificationsPG/CommunicatingwithAPNs.html
11. pn-provider, pn-param and pn-prid URI Parameters for Google 11. pn-provider, pn-param and pn-prid URI Parameters for Google
Firebase Cloud Messaging (FCM) push notification service Firebase Cloud Messaging (FCM) push notification service
When Firebase Cloud Messaging (FCM) is used, the PNS related URI When Firebase Cloud Messaging (FCM) is used, the PNS related URI
parameters are set as described below. parameters are set as described below.
For detailed information about the parameter values:
https://firebase.google.com/docs/cloud-messaging/concept-options
([pns-fcm])
The value of the pn-provider URI parameter is "fcm". The value of the pn-provider URI parameter is "fcm".
The value of the pn-param URI parameter is the Project ID. The value of the pn-param URI parameter is the Project ID.
The value of the pn-prid URI parameter is the Registration token, The value of the pn-prid URI parameter is the Registration token,
which is generated by the FCM SDK for each client app instance. which is generated by the FCM SDK for each client app instance.
For more information on the Project ID and Registration token:
https://firebase.google.com/docs/cloud-messaging/concept-options
12. pn-provider, pn-param and pn-prid URI Parameters for RFC 8030 12. pn-provider, pn-param and pn-prid URI Parameters for RFC 8030
(Generic Event Delivery Using HTTP Push) (Generic Event Delivery Using HTTP Push)
When Generic Event Delivery Using HTTP Push is used, the PNS related When Generic Event Delivery Using HTTP Push is used, the PNS related
URI parameters are set as described below. URI parameters are set as described below.
The value of the pn-provider URI parameter is "webpush". The value of the pn-provider URI parameter is "webpush".
The value of the pn-param URI parameter MUST NOT be used. The value of the pn-param URI parameter MUST NOT be used.
The value of the pn-prid URI parameter is the push subscription URI. The value of the pn-prid URI parameter is the push subscription URI.
See RFC 8030 for more details: See RFC 8030 [RFC8030] for more details.
Note that encryption for web push [RFC8291] is not used, therefore Note that encryption for web push [RFC8291] is not used, therefore
parameters for message encryption are not defined in this parameters for message encryption are not defined in this
specification. Web push permits the sending of a push message specification. Web push permits the sending of a push message
without a payload without encryption. without a payload without encryption.
13. Security Considerations 13. Security Considerations
Different mechanisms exist for authenticating and authorizing devices The security considerations for the use and operation of any
and users registering with a PNS. The mechanisms for authorizing and particular PNS (e.g., how users and devices are authenticated and
authenticating the users are PNS-specific, and are outside the scope authorized) is out of scope for this document. [RFC8030] documents
of this document. In addition to the information that needs to be the security considerations for the PNS defined in that
exchanged between a device and the PNS in order to establish a push specification. Security considerations for other PNSs are left to
notification subscription, the mechanism defined in this document their respective specifications.
does not require any additional information to be exchanged between
the device and the PNS.
Typically, the PNS also requires the SIP proxy requesting push Typically, the PNS requires the SIP proxy requesting push
notifications to be authenticated and authorized by the PNS. In some notifications to be authenticated and authorized by the PNS. In some
cases the PNS also require the SIP application (or the SIP cases the PNS also require the SIP application (or the SIP
application developer) to be identified in order for the application application developer) to be identified in order for the application
to request push notifications. to request push notifications. Unless the PNS authenticates and
authorizes the PNS, a malicious endpoint that managed to get access
Operators MUST ensure that the SIP signalling is properly secured, to the parameters transported in the SIP signalling might be able to
e.g., using encryption, from malicious middlemen. TLS MUST be used, request that push notifications are sent to a UA. Which such push
unless the operators know that the signalling is secured using some notifications will not have any security related impacts, they will
other mechanism. impact the battery life of the UA and trigger unnecessary SIP
traffic.
[RFC8292] defines a mechanism which allows a proxy to identity itself [RFC8292] defines a mechanism that allows a proxy to identity itself
to a PNS, by signing a JWT sent to the PNS using a key pair. The to a PNS, by signing a JWT sent to the PNS using a key pair. The
public key serves as an identifier of the proxy, and can be used by public key serves as an identifier of the proxy, and can be used by
devices to restrict push notifications to the proxy associated with devices to restrict push notifications to the proxy associated with
the key. the key.
The mechanism in this document does not require a proxy to include Operators MUST ensure that the SIP signalling is properly secured,
any payload (in addition to possible payload used for the PNS itself) e.g., using encryption, from malicious endpoints. TLS MUST be used,
when requesting push notifications. unless the operators know that the signalling is secured using some
other mechanism that provides strong crypto properties.
In addition to the information that needs to be exchanged between a
device and the PNS in order to establish a push notification
subscription, the mechanism defined in this document does not require
any additional information to be exchanged between the device and the
PNS.
The mechanism defined in this document does not require a proxy to
include any payload (in addition to possible payload used for the PNS
itself) when requesting push notifications.
Operators MUST ensure that the PNS-related SIP URI parameters
conveyed by a user in the Contact URI of a REGISTER request are not
sent to other users, or to non-trusted network entities. One way to
convey contact information is by using the the SIP event package for
registrations mechanism [RFC3680]. [RFC3680] defines generic
security considerations for the SIP event package for registations.
As the PMS-related SIP URI parameters conveyed in the REGISTER
request contain sensitive information, operators that support the
event package MUST ensure that event package subscriptions are
properly authenticated and authorized, and that the SIP URI
parameters are not included in event notifications sent to other
users, or to non-trusted network entities.
14. IANA considerations 14. IANA considerations
[RFC EDITOR NOTE: Please replace all instances of RFCXXXX with the
RFC number of this document.]
14.1. SIP URI Parameters 14.1. SIP URI Parameters
This section defines new SIP URI Parameters that extend the "SIP/SIPS This section defines new SIP URI Parameters that extend the "SIP/SIPS
URI Parameters" sub-registry [RFC3969] under the sip-parameters URI Parameters" sub-registry [RFC3969] under the sip-parameters
registry: http://www.iana.org/assignments/sip-parameters. registry: http://www.iana.org/assignments/sip-parameters.
14.1.1. pn-provider 14.1.1. pn-provider
Parameter Name: pn-provider Parameter Name: pn-provider
skipping to change at page 26, line 29 skipping to change at page 29, line 29
Contact: IESG (iesg@ietf.org) Contact: IESG (iesg@ietf.org)
14.3.2. sip.vapid 14.3.2. sip.vapid
This section defines a new feature-capability indicator that extends This section defines a new feature-capability indicator that extends
the "SIP Feature-Capability Indicator Registration Tree" sub-registry the "SIP Feature-Capability Indicator Registration Tree" sub-registry
[RFC6809] under the sip-parameters registry: [RFC6809] under the sip-parameters registry:
http://www.iana.org/assignments/sip-parameters. http://www.iana.org/assignments/sip-parameters.
Name: sip.vapid Name: sip.vapid
Description: This feature-capability indicator, when included in a Description: This feature-capability indicator, when included in a
SIP 2xx response to a SIP REGISTER request, indicates that the SIP 2xx response to a SIP REGISTER request, indicates that the
entity associated with the indicator supports, and will use, entity associated with the indicator supports, and will use,
the Voluntary Application Server Identification (VAPID) the Voluntary Application Server Identification (VAPID)
mechanism when requesting push notifications towards the SIP UA mechanism when requesting that a push notifications is sent to
associated with the SIP registration. The indicator value is a the SIP UA associated with the SIP registration. The indicator
public key identifying the entity, that can be used by a SIP UA value is a public key identifying the entity, that can be used
to restrict subscriptions to that entity. by a SIP UA to restrict subscriptions to that entity.
Reference: [RFCXXXX] Reference: [RFCXXXX]
Contact: IESG (iesg@ietf.org) Contact: IESG (iesg@ietf.org)
14.3.3. sip.pnsreg 14.3.3. sip.pnsreg
This section defines a new feature-capability indicator that extends This section defines a new feature-capability indicator that extends
the "SIP Feature-Capability Indicator Registration Tree" sub-registry the "SIP Feature-Capability Indicator Registration Tree" sub-registry
[RFC6809] under the sip-parameters registry: [RFC6809] under the sip-parameters registry:
http://www.iana.org/assignments/sip-parameters. http://www.iana.org/assignments/sip-parameters.
Name: sip.pnsreg Name: sip.pnsreg
Description: This feature-capability indicator, when included in a Description: This feature-capability indicator, when included in a
SIP 2xx response to a SIP REGISTER request, indicates that the SIP 2xx response to a SIP REGISTER request, indicates that the
entity associated with the indicator expects to receive entity associated with the indicator expects to receive
binding-refresh REGISTER requests from the SIP UA associated binding-refresh REGISTER requests from the SIP UA associated
with the registration before the registration expires, without with the registration before the registration expires, without
the entity having to request push notifications towards the SIP the entity having to request that a push notification is sent
UA in order to trigger the REGISTER requests. The indicator to the SIPvUA in order to trigger the REGISTER requests. The
value is the minimum value (given in seconds) before the indicator value is the minimum value (given in seconds) before
registration expireation when the entity expects to receive the the registration expireation when the entity expects to receive
REGISTER request. the REGISTER request.
Reference: [RFCXXXX] Reference: [RFCXXXX]
Contact: IESG (iesg@ietf.org) Contact: IESG (iesg@ietf.org)
14.3.4. sip.pnspurr 14.3.4. sip.pnspurr
This section defines a new feature-capability indicator that extends This section defines a new feature-capability indicator that extends
the "SIP Feature-Capability Indicator Registration Tree" sub-registry the "SIP Feature-Capability Indicator Registration Tree" sub-registry
[RFC6809] under the sip-parameters registry: [RFC6809] under the sip-parameters registry:
skipping to change at page 28, line 14 skipping to change at page 31, line 14
14.4. SIP Media Feature Tag 14.4. SIP Media Feature Tag
14.4.1. sip.pnsreg 14.4.1. sip.pnsreg
This section defines a new media feature tag that extends the "SIP This section defines a new media feature tag that extends the "SIP
Media Feature Tag Registration Tree" sub-registry [RFC3840] under the Media Feature Tag Registration Tree" sub-registry [RFC3840] under the
Media Feature Tag registry: https://www.iana.org/assignments/media- Media Feature Tag registry: https://www.iana.org/assignments/media-
feature-tags/media-feature-tags.xhtml. feature-tags/media-feature-tags.xhtml.
Media feature tag name: sip.pnsreg Media feature tag name: sip.pnsreg
Summary of the media feature indicated by this feature tag: This Summary of the media feature indicated by this feature tag: This
media feature tag, when included in the SIP Contact header media feature tag, when included in the SIP Contact header
field of a SIP REGISTER request, indicates that the SIP UA field of a SIP REGISTER request, indicates that the SIP UA
associated with the tag is able to send binding-refresh associated with the tag is able to send binding-refresh
REGISTER requests associated with the registration without REGISTER requests associated with the registration without
being awaken by push notifications. being awaken by push notifications.
Values appropriate for use with this feature tag: none Values appropriate for use with this feature tag: none
Related standards or documents: [RFCXXXX] Related standards or documents: [RFCXXXX]
Security considerations: This media feature tag does not introduce Security considerations: This media feature tag does not introduce
new security considerations, as it simply indicates support for new security considerations, as it simply indicates support for
a basic SIP feature. If an attacker manages to remove the media a basic SIP feature. If an attacker manages to remove the media
feature tag, push notifications towards the client will be feature tag, push notifications will not be requested to be sent
requested. to the client.
Contact: IESG (iesg@ietf.org) Contact: IESG (iesg@ietf.org)
14.5. PNS Sub-registry Establishment 14.5. PNS Sub-registry Establishment
This section creates a new sub-registry, "PNS", under the sip- This section creates a new sub-registry, "PNS", under the sip-
parameters registry: http://www.iana.org/assignments/sip-parameters. parameters registry: http://www.iana.org/assignments/sip-parameters.
The purpose of the sub-registry is to register SIP URI pn-provider The purpose of the sub-registry is to register SIP URI pn-provider
values. values.
When a SIP URI pn-provider value is registered in the sub-registry, When a SIP URI pn-provider value is registered in the sub-registry,
skipping to change at page 30, line 22 skipping to change at page 33, line 22
Protocol (SIP) "Replaces" Header", RFC 3891, Protocol (SIP) "Replaces" Header", RFC 3891,
DOI 10.17487/RFC3891, September 2004, <https://www.rfc- DOI 10.17487/RFC3891, September 2004, <https://www.rfc-
editor.org/info/rfc3891>. editor.org/info/rfc3891>.
[RFC3969] Camarillo, G., "The Internet Assigned Number Authority [RFC3969] Camarillo, G., "The Internet Assigned Number Authority
(IANA) Uniform Resource Identifier (URI) Parameter (IANA) Uniform Resource Identifier (URI) Parameter
Registry for the Session Initiation Protocol (SIP)", Registry for the Session Initiation Protocol (SIP)",
BCP 99, RFC 3969, DOI 10.17487/RFC3969, December 2004, BCP 99, RFC 3969, DOI 10.17487/RFC3969, December 2004,
<https://www.rfc-editor.org/info/rfc3969>. <https://www.rfc-editor.org/info/rfc3969>.
[RFC5079] Rosenberg, J., "Rejecting Anonymous Requests in the
Session Initiation Protocol (SIP)", RFC 5079,
DOI 10.17487/RFC5079, December 2007, <https://www.rfc-
editor.org/info/rfc5079>.
[RFC6809] Holmberg, C., Sedlacek, I., and H. Kaplan, "Mechanism to [RFC6809] Holmberg, C., Sedlacek, I., and H. Kaplan, "Mechanism to
Indicate Support of Features and Capabilities in the Indicate Support of Features and Capabilities in the
Session Initiation Protocol (SIP)", RFC 6809, Session Initiation Protocol (SIP)", RFC 6809,
DOI 10.17487/RFC6809, November 2012, <https://www.rfc- DOI 10.17487/RFC6809, November 2012, <https://www.rfc-
editor.org/info/rfc6809>. editor.org/info/rfc6809>.
[RFC8030] Thomson, M., Damaggio, E., and B. Raymor, Ed., "Generic [RFC8030] Thomson, M., Damaggio, E., and B. Raymor, Ed., "Generic
Event Delivery Using HTTP Push", RFC 8030, Event Delivery Using HTTP Push", RFC 8030,
DOI 10.17487/RFC8030, December 2016, <https://www.rfc- DOI 10.17487/RFC8030, December 2016, <https://www.rfc-
editor.org/info/rfc8030>. editor.org/info/rfc8030>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8292] Thomson, M. and P. Beverloo, "Voluntary Application Server [RFC8292] Thomson, M. and P. Beverloo, "Voluntary Application Server
Identification (VAPID) for Web Push", RFC 8292, Identification (VAPID) for Web Push", RFC 8292,
DOI 10.17487/RFC8292, November 2017, <https://www.rfc- DOI 10.17487/RFC8292, November 2017, <https://www.rfc-
editor.org/info/rfc8292>. editor.org/info/rfc8292>.
[pns-apns]
Apple Inc, "Apple Push Notification Service", January
2019, <https://developer.apple.com/library/archive/documen
tation/NetworkingInternet/Conceptual/
RemoteNotificationsPG/CommunicatingwithAPNs.html>.
[pns-fcm] Google Inc, "Firebase Cloud Messaging", January 2019, <
https://firebase.google.com/docs/cloud-messaging/concept-
options>.
16.2. Informative References 16.2. Informative References
[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
with Session Description Protocol (SDP)", RFC 3264, with Session Description Protocol (SDP)", RFC 3264,
DOI 10.17487/RFC3264, June 2002, <https://www.rfc- DOI 10.17487/RFC3264, June 2002, <https://www.rfc-
editor.org/info/rfc3264>. editor.org/info/rfc3264>.
[RFC3680] Rosenberg, J., "A Session Initiation Protocol (SIP) Event [RFC3680] Rosenberg, J., "A Session Initiation Protocol (SIP) Event
Package for Registrations", RFC 3680, Package for Registrations", RFC 3680,
DOI 10.17487/RFC3680, March 2004, <https://www.rfc- DOI 10.17487/RFC3680, March 2004, <https://www.rfc-
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