anchor.diff:  		    end,
   		    % XXX send new challenge (current behavior) or send 403 Forbidden when authentication fails?
   		    logger:log(Prio, "~s -> Authentication FAILED, sending challenge", [LogStr]),
  -		    ExtraHeaders = [{"WWW-Authenticate", sipheader:auth_print(sipauth:get_challenge(), false)},
  -		    		    {"Retry-After", ["3"]}],
  -		    transactionlayer:send_response_handler(THandler, 401, "Authentication Required", ExtraHeaders);
  +		    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]),
  
positive.code: 	    logger:log(debug, "Relay: STALE authentication, sending challenge"),
  	    logger:log(normal, "~s: incomingproxy: Relay ~s -> STALE authentication -> 407 Proxy Authentication Required",
  			[LogTag, sipurl:print(DstURI)]),
  	    ExtraHeaders = [{"Proxy-Authenticate", sipheader:auth_print(sipauth:get_challenge(), true)}],
  	    transactionlayer:send_response_handler(THandler, 407, "Proxy Authentication Required", ExtraHeaders);
  	false ->
  	    logger:log(debug, "Relay: Failed authentication, sending challenge"),
  	    logger:log(normal, "~s: incomingproxy: Relay ~s -> 407 Proxy Authorization Required", [LogTag, sipurl:print(DstURI)]),
  	    ExtraHeaders = [{"Proxy-Authenticate", sipheader:auth_print(sipauth:get_challenge(), false)}],
  	    transactionlayer:send_response_handler(THandler, 407, "Proxy Authentication Required", ExtraHeaders);
  	Unknown ->
  	    logger:log(error, "relay_request: Unknown result from sipauth:get_user_verified_proxy() :~n~p", [Unknown]),
  	    transactionlayer:send_response_handler(THandler, 500, "Server Internal Error")
  
negative.code: 		    end,
  		    logger:log(Prio, "~s -> Request from unauthorized homedomain user, sending challenge",
  		    		[LogStr]),
  		    transactionlayer:send_challenge_request(Request, proxy, false, none);
  		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")
  