REGISTER sip:example.com SIP/2.0
To: sip:j.user@example.com
From: sip:j.user@example.com;tag=87321hj23128
Max-Forwards: 8
Call-ID: regaut01.0ha0isndaksdj
CSeq: 9338 REGISTER
Via: SIP/2.0/TCP 192.0.2.253;branch=z9hG4bKkdjuw
Authorization: NoOneKnowsThisScheme opaque-data=here
Content-Length:0