SIP/2.0 404 Not Found
Via: SIP/2.0/UDP nm;branch=foo;received=224.4.99.27;rport=26810
From: <sip:nm@nm>;tag=root
To: <sip:nm2@nm2>;tag=as0f87c532
Call-ID: 50000
CSeq: 42 OPTIONS
Server: Aethra Telecommunications PBX
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO, UPDATE
Accept: application/sdp
Content-Length: 0