From Forum Nokia Wiki

ID	TSS000710	Creation date	July 4, 2007
Platform	S60 3rd Edition S60 3rd Edition, FP1	Devices
Category	Symbian C++	Subcategory	Networking

Keywords (APIs, classes, methods, functions):

Overview

SIP authentication with HTTP Digest credentials

Description

CSIPHttpDigest and MSIPHttpDigestChallengeObserver classes can be used for setting the Proxy Authentication Header parameters programmatically when a SIP client application is not using a SIP profile.

Solution

Create a CSIPHttpDigest object in ConstructL() of the engine class, derive from MSIPHttpDigestChallengeObserver, and implement the ChallengeReceived() callback function.
The SIP server in the signalling chain can challenge any SIP request initiated by the application with an HTTP Digest challenge by sending one of the following responses:
  401 (User Authentication Required)
  407 (Proxy Authentication Required)
  494 (Security Agreement Required)
When a SIP client receives the SIP response 407, 401, or 494 from the server, it automatically calls the MSIPHttpDigestChallengeObserver::ChallengeReceived() callback function.
If the client accepts the challenge, the callback function must call CSIPHttpDigest::SetCredentialsL(), specifying the user name, password, and the realm passed to the callback function. The SIP stack resends the original SIP request within the HTTP Digest response.
If the client rejects the challenge, the callback function must call CSIPHttpDigest::IgnoreChallenge(), specifying the realm passed to the callback function.
The SIP stack calls the callback function MSIPConnectionObserver::ErrorOccured(), passing the error code KErrSIPForbidden.
If the SIP client application does not wish to receive HTTP Digest challenges, it must not create a CSIPHttpDigest object. In this event, the SIP stack calls the callback function MSIPConnectionObserver::ErrorOccured(), passing the error code KErrSIPForbidden.