anchor.diff:  %% - 2xx response is provided to the TU
   %% - transaction terminates
   client_ok(Transport) ->
  -    register(?MODULE, self()),
  +    register(?REGNAME, self()),
   
       Remote = sip_test:endpoint(Transport),
       Request = sip_test:request('OPTIONS', Transport),
  
positive.code:                  sip_transaction:handle(undefined, Remote, Provisional)),
  
      ?assertReceive("Expect provisional response to be passed to TU",
      {tx, TxRef, {response, Provisional}}),
  
      % Emulate final 2xx response received by transport layer
      ?assertEqual({ok, TxRef},
  
negative.code:             ok % we have lots of message retransmissions in message queue
      end,
  
      unregister(?REGNAME),
      ok.
  
  %% Scenario tested:
  