failure_route[1]
{
	# authentication reply received?
	if ( t_check_status("401|407") )
	{
		# have we already tried to authenticate?
		if (isflagset(7))
		{
			t_reply("503","Authentication failed");
			exit;
		}
		if (uac_auth())
		{
			# mark that auth was performed
			setflag(7);
			# trigger again the failure route
			t_on_failure("1");
			# repeat the request with auth response this time
			append_branch();
			t_relay();
		}
	}
}