--- 1/draft-ietf-sipcore-status-unwanted-02.txt 2017-02-15 15:13:14.472303675 -0800 +++ 2/draft-ietf-sipcore-status-unwanted-03.txt 2017-02-15 15:13:14.488304050 -0800 @@ -1,18 +1,18 @@ SIPCORE H. Schulzrinne Internet-Draft FCC -Intended status: Standards Track January 12, 2017 -Expires: July 16, 2017 +Intended status: Standards Track February 15, 2017 +Expires: August 19, 2017 A SIP Response Code for Unwanted Calls - draft-ietf-sipcore-status-unwanted-02 + draft-ietf-sipcore-status-unwanted-03 Abstract This document defines the 666 (Unwanted) SIP response code, allowing called parties to indicate that the call or message was unwanted. SIP entities may use this information to adjust how future calls from this calling party are handled for the called party or more broadly. Status of This Memo @@ -22,93 +22,109 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on July 16, 2017. + This Internet-Draft will expire on August 19, 2017. Copyright Notice Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 - 2. Normative Language . . . . . . . . . . . . . . . . . . . . . 2 + 2. Normative Language . . . . . . . . . . . . . . . . . . . . . 3 3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Behavior of SIP Entities . . . . . . . . . . . . . . . . . . 3 - 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 - 5.1. SIP Response Code . . . . . . . . . . . . . . . . . . . . 4 - 5.2. SIP Global Feature-Capability Indicator . . . . . . . . . 4 + 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 + 5.1. SIP Response Code . . . . . . . . . . . . . . . . . . . . 5 + 5.2. SIP Global Feature-Capability Indicator . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 - 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 + 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 8.1. Normative References . . . . . . . . . . . . . . . . . . 6 - 8.2. Informative References . . . . . . . . . . . . . . . . . 6 + 8.2. Informative References . . . . . . . . . . . . . . . . . 7 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7 1. Introduction In many countries, an increasing number of calls are unwanted [RFC5039]: they might be fraudulent, illegal telemarketing or the receiving party does not want to be disturbed by, say, surveys or solicitation by charities. Carriers and other service providers may want to help their subscribers avoid receiving such calls, using a variety of global or user-specific filtering algorithms. One input into such algorithms is user feedback. User feedback may be offered through smartphone apps, APIs or within the context of a SIP- initiated call. This document addresses only the last mode, where the called party either rejects the SIP [RFC3261] request, typically requests using the INVITE or MESSAGE methods, as unwanted or terminates the session with a BYE request after answering the call. To allow the called party to express that the call was unwanted, this document defines the 666 (Unwanted) response code. The called user agent (UAS), based on input from the called party or some UA-internal - logic, uses this to indicate that future calls from the same caller - are also unwanted. + logic, uses this to indicate that this call is unwanted and that + future attempts are likely to be similarly rejected. While factors + such as identity spoofing and call forwarding may make authoritative + identification of the calling party difficult or impossible, the + network can use such a rejection -- possibly combined with a pattern + of rejections by other callees and/or other information -- as input + to a heuristic algorithm for determining future call treatment. The + heuristic processing and possible treatment of persistently unwanted + calls are outside the scope of this document. As in [I-D.ietf-stir-rfc4474bis], we use the term "caller identity" or "calling party identity" in this document to mean either a canonical address-of-record (AoR) SIP URI employed to reach a user (such as 'sip:alice@atlanta.example.com'), or a telephone number, which commonly appears in either a tel URI [RFC3966] or as the user portion of a SIP URI. 2. Normative Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14, RFC 2119 [RFC2119]. 3. Motivation None of the existing 4xx, 5xx or 6xx response codes signify that this - SIP request is unwanted by the called party. The particular response - code number was chosen to reflect the distaste felt by many upon - receiving such calls. + SIP request is unwanted by the called party. For example, 603 + (Decline) might be used if the called party is currently at dinner or + in a meeting, but does not want to indicate any specific reason. As + described in Section 21.6.2 [RFC3261], a 603 response may include a + Retry-After header field to indicate a better time to attempt the + call. Thus, the call is rejected due to the called party's + (temporary) disposition. As described in Section 4, the called party + invokes the "unwanted call" user interface and 666 (Unwanted) + response indicating that it is instead the caller's identity that is + causing the call to be rejected. The particular response code number + was chosen to reflect the distaste felt by many upon receiving such + calls. 4. Behavior of SIP Entities The response code 666 MAY be used in a failure response for an INVITE, MESSAGE, SUBSCRIBE or other out-of-dialog SIP request to indicate that the offered communication is unwanted. The response code MAY also be used as the value of the "cause" parameter of a SIP reason-value in a Reason header field [RFC3326], typically when the UAS issues a BYE request terminating an incoming call or the UAC issues a CANCEL request when forking a call. (Including a Reason @@ -120,20 +136,31 @@ take any particular action beyond those appropriate for 6xx responses. Following the default handling for 6xx responses in [RFC5057], the 666 response destroys the transaction. The service provider delivering calls or messages to the user issuing the response, for example, MAY add the calling party to a personal blacklist specific to the called party, MAY use the information as input when computing the likelihood that the calling party is placing unwanted calls ("crowd sourcing"), MAY initiate a traceback request, and MAY report the calling party identity to government authorities. + This specification does not mandate any particular action by SIP + entities and leaves those to implementations. Call handling for + unwanted calls is likely to involve a combination of heuristics, + analytics, machine learning, based on user feedback, call + characteristics such as call duration and call volumes, as well + changes in such metrics. Implementations will have to make + appropriate trade-offs between falsely labeling a caller as unwanted + and delivering unwanted calls. The user experience is envisioned to + be somewhat similar to email spam buttons where the detailed actions + of the email provider remain opaque to the user. + Systems receiving 666 responses could decide to treat pre-call and mid-call responses differently, given that the called party has had access to call content for mid-call rejections. In other words, depending on the implementation, the response code does not necessarily automatically block all calls from that caller identity. The same user interface action might also trigger addition of the caller identity to a local, on-device blacklist or graylist, e.g., causing such calls to be flagged or alerted with a different ring tone. @@ -213,20 +240,25 @@ accordingly, e.g., by comparing the fraction of delivered calls for a particular caller that are flagged as unwanted rather than just the absolute number, and considering time-weighted filters that give more credence to recent feedback. Since caller identities are routinely re-assigned to new subscribers, algorithms are advised to consider whether the caller identity has been re-assigned to a new subscriber and possibly reset any related rating. + Some call services such as 3PCC [RFC3725] and call transfer increase + the complexity of identifying who (if anyone) should be impacted by + the receipt of 666 within BYE. Such services might causes the wrong + party to be flagged or prevent flagging the desired party. + For both individually-authenticated and unauthenticated calls, recipients of response code 666 may want to distinguish responses sent before and after the call has been answered, ascertaining whether either response timing suffers from a lower false-positive rate. 7. Acknowledgements Tolga Asveren, Peter Dawes, Martin Dolly, Keith Drage, Vijay Gurbani, Olle Johansson, Paul Kyzivat, Jean Mahoney, Marianne Mohali, Brian @@ -261,35 +293,40 @@ Indicate Support of Features and Capabilities in the Session Initiation Protocol (SIP)", RFC 6809, DOI 10.17487/RFC6809, November 2012, . 8.2. Informative References [I-D.ietf-stir-rfc4474bis] Peterson, J., Jennings, C., Rescorla, E., and C. Wendt, "Authenticated Identity Management in the Session - Initiation Protocol (SIP)", draft-ietf-stir-rfc4474bis-15 - (work in progress), October 2016. + Initiation Protocol (SIP)", draft-ietf-stir-rfc4474bis-16 + (work in progress), February 2017. [RFC3323] Peterson, J., "A Privacy Mechanism for the Session Initiation Protocol (SIP)", RFC 3323, DOI 10.17487/RFC3323, November 2002, . + [RFC3725] Rosenberg, J., Peterson, J., Schulzrinne, H., and G. + Camarillo, "Best Current Practices for Third Party Call + Control (3pcc) in the Session Initiation Protocol (SIP)", + BCP 85, RFC 3725, DOI 10.17487/RFC3725, April 2004, + . + [RFC3966] Schulzrinne, H., "The tel URI for Telephone Numbers", RFC 3966, DOI 10.17487/RFC3966, December 2004, . [RFC5039] Rosenberg, J. and C. Jennings, "The Session Initiation Protocol (SIP) and Spam", RFC 5039, DOI 10.17487/RFC5039, January 2008, . Author's Address - Henning Schulzrinne FCC 445 12th Street SW Washington, DC 20554 US Email: henning.schulzrinne@fcc.gov