SIP/2.0 403 SIP request not received from active SIP server
Via: SIP/2.0/UDP nm;branch=foo;rport
From: <sip:nm@nm>;tag=root
To: <sip:nm2@nm2>;tag=b72e12N266731c2dd-20876bc8
Call-ID: 50000
CSeq: 42 OPTIONS
Content-Length: 0

HTTP/1.1 401 Authorization Required
Content-Length: 0
Server: TR069 client TCP connection request Server
WWW-Authenticate: Digest realm="TR069 Client", qop="auth", nonce="yctlsxejUhNOV/Fb8zf1ZmIzFLdW1Sx", algorithm="MD5", domain="/"
Connection: close