%% You should probably cite draft-ietf-martini-gin instead of this I-D.
@techreport{roach-martini-gin-02,
    number =    {draft-roach-martini-gin-02},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-roach-martini-gin/02/},
    author =    {Adam Roach},
    title =     {{Registration for Multiple Phone Numbers in the Session Initiation Protocol (SIP)}},
    pagetotal = 19,
    year =      2010,
    month =     mar,
    day =       24,
    abstract =  {This document defines a mechanism by which a SIP server acting as a traditional Private Branch Exchange (PBX) can register with a SIP Service Provider (SSP) to receive phone calls for extensions designated by phone numbers. In order to function properly, this mechanism relies on the fact that the phone numbers are fully qualified and globally unique.},
}