anchor.diff:  %% @private
   -spec do_send_work_sync(pid(), nksip:srv_id(), nksip:call_id(), nksip_call_worker:work(), 
                           {pid(), term()}, #state{}) ->
  -    #state{}.
  +    {ok, #state{}}.
   
   do_send_work_sync(CallPid, SrvId, CallId, Work, From, #state{works=Works}=State) ->
       Ref = make_ref(),
  
positive.code:     {ok, #state{}} | {error, too_many_calls}.
  
  do_call_start(SrvId, SrvPid, CallId, Work, From, State) ->
      #state{name=Name, services=Srvs} = State,
      Max = nksip_config_cache:global_max_calls(),
      case nklib_counters:value(nksip_calls) < Max of
          true ->
  
negative.code:     {ok, #state{}} | {error, looped_process | service_not_found | too_many_calls}.
  
  send_work_sync(SrvId, CallId, Work, Caller, From, #state{name=Name}=State) ->
      case find_call_pid(Name, SrvId, CallId) of
          {ok, Caller} ->
              {error, looped_process};
          {ok, CallPid} -> 
  