REGISTER sip:example.com SIP/2.0
To: sip:user@example.com
From: sip:user@example.com;tag=998332
Max-Forwards: 70
Call-ID: regbadct.k345asrl3fdbv@10.0.0.1
CSeq: 1 REGISTER
Via: SIP/2.0/UDP 135.180.130.133:5060;branch=z9hG4bKkdjuw
Contact: sip:user@example.com?Route=%3Csip:sip.example.com%3E
l: 0