%% You should probably cite rfc3578 instead of this I-D.
@techreport{ietf-sipping-overlap-04,
    number =    {draft-ietf-sipping-overlap-04},
    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-sipping-overlap/04/},
    author =    {Jon Peterson and Gonzalo Camarillo and Adam Roach and Lyndon Ong},
    title =     {{Mapping of Integrated Services Digital Network (ISDN) User Part (ISUP) Overlap Signalling to the Session Initiation Protocol (SIP)}},
    pagetotal = 13,
    year =      2003,
    month =     feb,
    day =       3,
    abstract =  {This document describes a way to map Integrated Services Digital Network User Part (ISUP) overlap signalling to Session Initiation Protocol (SIP). This mechanism might be implemented when using SIP in an environment where part of the call involves interworking with the Public Switched Telephone Network (PSTN). {[}STANDARDS-TRACK{]}},
}