%% You should probably cite rfc8688 instead of this I-D. @techreport{ietf-sipcore-rejected-05, number = {draft-ietf-sipcore-rejected-05}, type = {Internet-Draft}, institution = {Internet Engineering Task Force}, publisher = {Internet Engineering Task Force}, note = {Work in Progress}, url = {https://datatracker.ietf.org/doc/draft-ietf-sipcore-rejected/05/}, author = {Eric Burger and Bhavik Nagda}, title = {{A Session Initiation Protocol (SIP) Response Code for Rejected Calls}}, pagetotal = 22, year = 2019, month = mar, day = 31, abstract = {This document defines the 608 (Rejected) SIP response code. This response code enables calling parties to learn that an intermediary rejected their call attempt. The call will not be answered. As a 6xx code, the caller will be aware that future attempts to contact the same UAS will likely fail. The present use case driving the need for the 608 response code is when the intermediary is an analytics engine. In this case, the rejection is by a machine or other process. This contrasts with the 607 (Unwanted) SIP response code, which a human at the target UAS indicated the call was not wanted. In some jurisdictions this distinction is important. This document also defines the use of the Call-Info header in 608 responses to enable rejected callers to contact entities that blocked their calls in error. This provides a remediation mechanism for legal callers that find their calls blocked.}, }