A SIP Response Code for Unwanted Calls
RFC 8197
Internet Engineering Task Force (IETF) H. Schulzrinne
Request for Comments: 8197 FCC
Category: Standards Track July 2017
ISSN: 2070-1721
A SIP Response Code for Unwanted Calls
Abstract
This document defines the 607 (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
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc8197.
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
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Schulzrinne Standards Track [Page 1]
RFC 8197 Status Unwanted July 2017
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Normative Language . . . . . . . . . . . . . . . . . . . . . 3
3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Behavior of SIP Entities . . . . . . . . . . . . . . . . . . 3
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5.1. SIP Response Code . . . . . . . . . . . . . . . . . . . . 5
5.2. SIP Global Feature-Capability Indicator . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . 7
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
In many countries, an increasing number of calls are unwanted
[RFC5039]: they might be fraudulent or illegal telemarketing or maybe
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 feedback within the SIP
call. Here, the called party either rejects the SIP [RFC3261]
request as unwanted or terminates the session with a BYE request
after answering the call. INVITE and MESSAGE requests are most
likely to trigger such a response.
To allow the called party to express that the call was unwanted, this
document defines the 607 (Unwanted) response code. The user agent
(UA) of the called party, based on input from the called party or
some UA-internal 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.
Schulzrinne Standards Track [Page 2]
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When this document refers to "caller identity", it uses "identity" in
the same sense as [SIP-IDENTITY], i.e., to mean either a canonical
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