%% You should probably cite rfc5630 instead of this I-D.
@techreport{ietf-sip-sips-09,
    number =    {draft-ietf-sip-sips-09},
    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-sip-sips/09/},
    author =    {Francois Audet},
    title =     {{The Use of the SIPS URI Scheme in the Session Initiation Protocol (SIP)}},
    pagetotal = 56,
    year =      2008,
    month =     nov,
    day =       25,
    abstract =  {This document provides clarifications and guidelines concerning the use of the SIPS URI scheme in the Session Initiation Protocol (SIP). It also makes normative changes to SIP. {[}STANDARDS-TRACK{]}},
}