anchor.diff:      SipC2 = "sip:127.0.0.1:5070",
       Ref = make_ref(),
       Self = self(),
  -    Hd1 = {"x-nk-reply", base64:encode(erlang:term_to_binary({Ref, Self}))},
  -    Hd2 = {"x-nk-op", "expires-2"},
  +    Hd1 = {add, "x-nk-reply", base64:encode(erlang:term_to_binary({Ref, Self}))},
  +    Hd2 = {add, "x-nk-op", "expires-2"},
       {ok, 200, [{subscription_id, Subs1A}]} = 
  -        nksip_uac:subscribe(C1, SipC2, [{event, "myevent4"}, {expires, 5},
  -                                        {add, Hd1}, {add, Hd2}]),
  +        nksip_uac:subscribe(C1, SipC2, [{event, "myevent4"}, {expires, 5}, Hd1, Hd2]),
       Subs1B = nksip_subscription:remote_id(C1, Subs1A),
       {ok, 200, []} = nksip_uac:notify(C2, Subs1B, []),
   
  
positive.code:                                         {contact, "sip:a@127.0.0.1"}, 
                                          {meta, [dialog_id]}]),
      Subs1B = nksip_subscription:remote_id(C1, Subs1A),
      RS1 = {"record-route", "<sip:b1@127.0.0.1:5070;lr>,<sip:b@b>,<sip:a2@127.0.0.1;lr>"},
  
      % Now the remote party (the server) sends a NOTIFY, and updates the Route Set
      {ok, 200, []} = nksip_uac:notify(C2, Subs1B, [{add, RS1}]),
      [
          {local_target, <<"<sip:a@127.0.0.1>">>},
          {remote_target, <<"<sip:127.0.0.1:5070>">>},
  
negative.code:     SipC2 = "sip:127.0.0.1:5070",
      Self = self(),
      Ref = make_ref(),
      ReplyHd = {add, "x-nk-reply", base64:encode(erlang:term_to_binary({Ref, Self}))},
      CB = {callback, fun(R) -> Self ! {Ref, R} end},
  
      {async, _} = 
          nksip_uac:subscribe(C1, SipC2, [{event, "myevent4"}, CB, async, get_request,
                                          ReplyHd, {add, "x-nk-op", "wait"}, 
                                          {expires, 2}]),
  
      % Right after sending the SUBSCRIBE, and before replying with 200
  