%% You should probably cite rfc7255 instead of this I-D.
@techreport{allen-dispatch-imei-urn-as-instanceid-13,
    number =    {draft-allen-dispatch-imei-urn-as-instanceid-13},
    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/13/},
    author =    {Andrew Allen},
    title =     {{Using the International Mobile station Equipment Identity (IMEI) Uniform Resource Name (URN) as an Instance ID}},
    pagetotal = 9,
    year =      2014,
    month =     feb,
    day =       27,
    abstract =  {This specification defines how the Uniform Resource Name (URN) reserved for the Global System for Mobile Communications Association (GSMA) identities and its sub-namespace for the International Mobile station Equipment Identity (IMEI) can be used as an instance-id. Its purpose is to fulfill the requirements for defining how a specific URN needs to be constructed and used in the '+sip.instance' Contact header field parameter for outbound behavior.},
}