REGISTER sip:example.com SIP/2.0
To: isbn:2983792873
From: <http://www.example.com>;tag=3234233
Call-ID: unksm2.daksdj@hyphenated-host.example.com
CSeq: 234902 REGISTER
Max-Forwards: 70
Via: SIP/2.0/UDP 192.0.2.21:5060;branch=z9hG4bKkdjuw
Contact: <name:John_Smith>
l: 0
