@techreport{holmberg-ecrit-callback-00,
    number =    {draft-holmberg-ecrit-callback-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-holmberg-ecrit-callback/00/},
    author =    {Christer Holmberg},
    title =     {{Session Initiation Protocol (SIP) Media Feature Tag to identity a Public Safety Answering Point (PSAP) Callback Call}},
    pagetotal = 8,
    year =      2011,
    month =     may,
    day =       3,
    abstract =  {This specification defines a new Session Initiation Protocol (SIP) media feature tag, sip.psap.callback, that SIP entities can use to identity Public Safety Answering Point (PSAP) callback calls, and to associate them with a previously made emergency call.},
}