@misc{rfc6223,
    series =    {Request for Comments},
    number =    6223,
    howpublished =  {RFC 6223},
    publisher = {RFC Editor},
    doi =       {10.17487/RFC6223},
    url =       {https://www.rfc-editor.org/info/rfc6223},
    author =    {Christer Holmberg},
    title =     {{Indication of Support for Keep-Alive}},
    pagetotal = 18,
    year =      2011,
    month =     apr,
    abstract =  {This specification defines a new Session Initiation Protocol (SIP) Via header field parameter, "keep", which allows adjacent SIP entities to explicitly negotiate usage of the Network Address Translation (NAT) keep-alive mechanisms defined in SIP Outbound, in cases where SIP Outbound is not supported, cannot be applied, or where usage of keep-alives is not implicitly negotiated as part of the SIP Outbound negotiation. {[}STANDARDS-TRACK{]}},
}