INVITE sip:user@domain SIP/2.0
Via: SIP / 2.0 / UDP host.test.com  ;   branch=0   ,  
  SIP/2.0/TCP   host2.test2.com    ; branch=1
From   :   Caller  <sip:caller@domain.com>
To: Callee <sip:callee@domain>
Call-ID: 86888aab87@10.0.1.1
CSeq: 0    INVITE
Content-Length: 0