OPTIONS sip:ks SIP/2.0
Via: SIP/2.0/TCP ks;branch=foo
From: <sip:ad@ba>;tag=root
To: <sip:ad3@ba1>
Call-ID: 50000
CSeq: 42 OPTIONS
Max-Forwards: 70
Content-Length: 0
Contact: <sip:ad@ba>
Accept: application/sdp