SIP/2.0 403 Forbidden
Via: SIP/2.0/UDP nm;received=224.10.112.4;branch=foo;rport=26810
From: <sip:nm@nm>;tag=root
To: <sip:nm2@nm2>;tag=aprqngfrt-c8fdbh00000k2
Call-ID: 50000
CSeq: 42 OPTIONS