%% You should probably cite rfc7255 instead of this I-D.
@techreport{allen-dispatch-imei-urn-as-instanceid-06,
    number =    {draft-allen-dispatch-imei-urn-as-instanceid-06},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-allen-dispatch-imei-urn-as-instanceid/06/},
    author =    {Andrew Allen},
    title =     {{Using the International Mobile station Equipment Identity(IMEI)URN as an Instance ID}},
    pagetotal = 9,
    year =      2012,
    month =     oct,
    day =       12,
    abstract =  {This specification defines how the Uniform Resource Name namespace reserved for GSMA (Global Sstandard for Mobiles Association) identities and its sub namespace for the IMEI (International Mobile station Equipment Identity) can be used as an instance-id as specified in RFC 5626 {[}1{]} and also as used by RFC 5627 {[}2{]}. Its purpose is to fulfil the requirements in RFC 5626 {[}1{]} that state "If a URN scheme other than UUID is used, the UA MUST only use URNs for which an RFC (from the IETF stream) defines how the specific URN needs to be constructed and used in the "+sip.instance" Contact header field parameter for outbound behavior."},
}