%% You should probably cite draft-ietf-sipcore-rejected instead of this I-D.
@techreport{burger-sipcore-rejected-00,
    number =    {draft-burger-sipcore-rejected-00},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-burger-sipcore-rejected/00/},
    author =    {Eric Burger},
    title =     {{A Session Initiation Protocol (SIP) Response Code for Rejected Calls}},
    pagetotal = 15,
    year =      ,
    month =     ,
    day =       ,
    abstract =  {This document defines the 608 (Rejected) SIP response code. This response code enables calling parties to learn their call was rejected by an intermediary and will not be answered. As a 6xx code, the caller will be aware that future attempts to contact the same UAS will be likely to fail. The present use case driving the need for the 608 response code is when the intermediary is an analytics engine. In other words, the rejection is by a machine or other process, as opposed to a human at the target UAS indicating the call was not wanted. 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.},
}