SIP/2.0 404 Not Found
From: <sip:nm@nm>;tag=root
To: <sip:nm2@nm2>;tag=a611a0-0-13c4-50029-3d037-6866a17f-3d037
Call-ID: 50000
CSeq: 42 OPTIONS
Via: SIP/2.0/UDP nm;received=224.76.122.226;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

HTTP/1.1 407 OK
Date: Wed, 20 Jan 2021 05:55:41 GMT
Content-Type: text/plain; charset=utf-8
Content-Length: 34
Connection: keep-alive