anchor.diff:  		    end;
   		{stale, _} ->
   		    logger:log(normal, "~s -> Authentication is STALE, sending new challenge", [LogStr]),
  -		    ExtraHeaders = [{"WWW-Authenticate", sipheader:auth_print(sipauth:get_challenge(), true)}],
  -		    transactionlayer:send_response_handler(THandler, 401, "Authentication Required", ExtraHeaders);
  +		    transactionlayer:send_challenge(THandler, www, true, none);
   		{{false, eperm}, SipUser} when SipUser /= none ->
   		    logger:log(normal, "~s: incomingproxy: SipUser ~p NOT ALLOWED to REGISTER address ~s",
   				[LogTag, SipUser, sipurl:print(ToURL)]),
  
positive.code: 		    end,
  		    logger:log(Prio, "~s -> Request from unauthorized homedomain user, sending challenge",
  		    		[LogStr]),
  		    ExtraHeaders = [{"Proxy-Authenticate", sipheader:auth_print(sipauth:get_challenge(), false)}],
  		    transactionlayer:send_response_request(Request, 407, "Proxy Authentication Required", ExtraHeaders);
  		Unknown ->
  		    logger:log(error, "request: Unknown result from local:get_user_verified_proxy() :~n~p", [Unknown]),
  		    transactionlayer:send_response_request(Request, 500, "Server Internal Error")
  
negative.code: 		    end,
  		    % XXX send new challenge (current behavior) or send 403 Forbidden when authentication fails?
  		    logger:log(Prio, "~s -> Authentication FAILED, sending challenge", [LogStr]),
  		    transactionlayer:send_challenge(THandler, www, false, 3);
  		Unknown ->
  		    logger:log(error, "Register: Unknown result from local:can_register() URL ~p :~n~p",
  		    		[sipurl:print(URL), Unknown]),
  