Probe capture:SIP/2.0 200 OK
Via: SIP/2.0/UDP nm;branch=foo;received=224.157.165.143;rport=26810
From: <sip:nm@nm>;tag=root
To: <sip:nm2@nm2>;tag=as50075a46
Call-ID: 50000
CSeq: 42 OPTIONS
User-Agent: AVA media PBX
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY
Supported: replaces
Contact: <sip:61.220.205.76>
Accept: application/sdp
Content-Length: 0