OPTIONS sip:t.watson@example.org SIP/7.0
Via:     SIP/7.0/UDP c.example.com;branch=z9hG4bKkdjuw
Max-Forwards:     70
From:    A. Bell <sip:a.g.bell@example.com>;tag=qweoiqpe
To:      T. Watson <sip:t.watson@example.org>
Call-ID: badvers.31417@c.example.com
CSeq:    1 OPTIONS
l: 0
