unknow

SIP/2.0 404 Not Found
From: <sip:nm@nm>;tag=root
To: <sip:nm2@nm2>;tag=9ec808-0-13c4-50029-cafba-5dbdeb79-cafba
Call-ID: 50000
CSeq: 42 OPTIONS
Via: SIP/2.0/UDP nm;received=224.10.189.212;rport=26810;branch=foo
Supported: replaces,100rel,timer
Accept: application/sdp
Allow: INVITE,ACK,CANCEL,BYE,OPTIONS,REFER,INFO,NOTIFY,PRACK,MESSAGE
Content-Length: 0