SIP/2.0 404 Not Found
Via: SIP/2.0/UDP nm:5060;branch=foo;received=224.94.144.209;rport=26810
From: <sip:nm@nm>;tag=root
To: <sip:nm2@nm2>;tag=b72e12N266619ab52-6701a1b3
Call-ID: 50000
CSeq: 42 OPTIONS
Accept: multipart/mixed,application/sdp,application/simple-message-summary,application/broadsoft,application/dialog-info+xml,application/simservs+xml,application/vnd.etsi.aoc+xml;sv=2,application/vnd.etsi.aoc+xml;schemaversion=2,application/vnd.etsi.aoc+xml
Allow: INVITE,ACK,CANCEL,BYE,PRACK,UPDATE,SUBSCRIBE
Supported: 100rel,timer
Content-Length: 0

HTTP/1.0 401 Unauthorized
Content-type: text/html
Date: Thu, 04 Apr 2024 11:04:47 GMT
Connection: close
WWW-Authenticate: Digest realm="SERCOMM CPE Authentication",nonce="1712228687",algorithm="MD5",qop="auth"