User-Name = "test",
Digest-Response = "631d6d73147add2f9e437f59bbc3aeb7",
Digest-Realm = "testrealm",
Digest-Nonce = "1234abcd",
Digest-Method = "INVITE",
Digest-URI = "sip:5555551212@example.com",
Digest-Algorithm = "MD5",
Digest-User-Name = "test",
Message-Authenticator = ""