SIP/2.0 404 Not Found
From: <sip:nm@nm>;tag=root
To: <sip:nm2@nm2>;tag=a276c0-3979558-13c4-5506-1c826d-56ece643-1c826d
Call-ID: 50000
CSeq: 42 OPTIONS
User-Agent: Epicentro - YAPS ADB Stack
Supported: replaces,timer,100rel
Via: SIP/2.0/UDP nm;received=224.252.128.184;rport=26810;branch=foo
Content-Length: 0

HTTP/1.1 401 Unauthorized
Server: YAPS
WWW-Authenticate: Digest realm="YapsieWorld", qop="auth", nonce="f201e40fd58a15437324aad86372b8d3", opaque="a030521ebb196207aac5231cb9f4ef60"
Content-Length: 0
Connection: close