@techreport{johnston-sipping-cc-conferencing-01,
    number =    {draft-johnston-sipping-cc-conferencing-01},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-johnston-sipping-cc-conferencing/01/},
    author =    {Orit Levin},
    title =     {{Session Initiation Protocol Call Control -  
Conferencing for User Agents}},
    pagetotal = 24,
    year =      2003,
    month =     feb,
    day =       11,
    abstract =  {This document defines conferencing call control features for the Session Initiation Protocol (SIP). This document builds on the Conferencing Requirements and Framework documents to define how a tightly coupled SIP conference works. The approach is explored from different user agent (UA) types perspective: conference-unaware, conference-aware and focus UAs. The use of URIs in conferencing, OPTIONS for capabilities discovery, and call control using REFER are covered in detail with example call flow diagrams.},
}