%% You should probably cite rfc4780 instead of this I-D.
@techreport{ietf-sip-mib-12,
    number =    {draft-ietf-sip-mib-12},
    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-mib/12/},
    author =    {Jean-Francois Mule and Joon Maeng and Dave R. Walker and Kevin Lingle},
    title =     {{Management Information Base for the Session Initiation Protocol (SIP)}},
    pagetotal = 83,
    year =      2006,
    month =     sep,
    day =       18,
    abstract =  {This memo defines a portion of the Management Information Base (MIB) for use with network management protocols in the Internet community. In particular, it describes a set of managed objects that are used to manage Session Initiation Protocol (SIP) entities, which include User Agents, and Proxy, Redirect and Registrar servers. {[}STANDARDS-TRACK{]}},
}