The user must implement this interface if it intends to provide HTTP Digest credentials upon received challenges from the SIP servers on the signaling path. The user should provide credentials or ignore the challenge using functions defined in TSIPHttpDigest class.

MSIPHttpDigestChallengeObserver class is compliant with RFC 2543 where Proxy use to forward only one challenge when it receives multiple challenges on forking the request. Applications are encouraged to use MSIPHttpDigestChallengeObserver2 class which provides interface to extract multiple challenges. MSIPHttpDigestChallengeObserver2 class is compliant to RFC 3261 n/a