@misc{rfc4508,
    series =    {Request for Comments},
    number =    4508,
    howpublished =  {RFC 4508},
    publisher = {RFC Editor},
    doi =       {10.17487/RFC4508},
    url =       {https://www.rfc-editor.org/info/rfc4508},
    author =    {Alan Johnston and Orit Levin},
    title =     {{Conveying Feature Tags with the Session Initiation Protocol (SIP) REFER Method}},
    pagetotal = 6,
    year =      2006,
    month =     may,
    abstract =  {The SIP "Caller Preferences" extension defined in RFC 3840 provides a mechanism that allows a SIP request to convey information relating to the originator's capabilities and preferences for handling of that request. The SIP REFER method defined in RFC 3515 provides a mechanism that allows one party to induce another to initiate a SIP request. This document extends the REFER method to use the mechanism of RFC 3840. By doing so, the originator of a REFER may inform the recipient as to the characteristics of the target that the induced request is expected to reach. {[}STANDARDS-TRACK{]}},
}