A Session Initiation Protocol (SIP) Response Code for Call Rating

Document Type Expired Internet-Draft (individual)
Author Russ Penar 
Last updated 2020-12-26 (latest revision 2020-06-24)
Stream (None)
Intended RFC status (None)
Expired & archived
pdf htmlized bibtex
Stream Stream state (No stream defined)
Consensus Boilerplate Unknown
RFC Editor Note (None)
IESG IESG state Expired
Telechat date
Responsible AD (None)
Send notices to (None)

This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


This document defines the 120 (Rated) Session Initiation Protocol (SIP) response code. This response code enables calling parties to learn an intermediary rated their call attempt. Depending on rating (e.g. Scam), the call may go unanswered. Through a 1xx code, the caller's network may become aware future attempts to contact the same User Agent Server (UAS) will likely go unanswered. The initial use case driving the need for a 120 response code is when the intermediary is an analytics engine. Code 120 (Rated) contrasts with 607 (Unwanted) & 608 (Rejected) SIP response codes in which a human at target UAS, or terminating network analytics, indicate the call may not completed. This document also defines use of a Call-Info header field in 120 (Rated) responses to enable negatively rated callers to contact entities that rated their calls in error. This provides a remediation mechanism for legal callers who find their calls going unanswered (not necessarily blocked).


Russ Penar (russp@microsoft.com)

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)