SIP/2.0 200 Ok
Via: SIP/2.0/UDP foo.bar.com
Via: SIP/2.0/UDP mobile55
From: <sip:x@foo.bar>
To: <sip:y@bar.foo>
Call-ID:9437892232b@foo.bar
CSeq: 143 INVITE
Contact: <sip:x@foo.bar>