anchor.diff:  			end,
   			[{'Origin-Realm', OriginRealm} | Options1]
   	end,
  -	Module = case NrfUri of
  -		undefined ->
  -			?RO_APPLICATION_CALLBACK;
  -		NrfUri when is_list(NrfUri) ->
  -			?NRF_RO_APPLICATION_CALLBACK
  +	Options3 = case lists:keyfind(callback, 1, Options2) of
  +		{callback, CallBack} ->
  +			[{application, [{alias, ?RO_APPLICATION},
  +					{dictionary, ?RO_APPLICATION_DICT},
  +					{module, CallBack},
  +					{request_errors, callback}]} | Options2];
  +		false ->
  +			[{application, [{alias, ?RO_APPLICATION},
  +					{dictionary, ?RO_APPLICATION_DICT},
  +					{module, ?RO_APPLICATION_CALLBACK},
  +					{request_errors, callback}]} | Options2]
   	end,
  -	Options2 ++ [{'Vendor-Id', ?IANA_PEN_SigScale},
  +	Options3 ++ [{'Vendor-Id', ?IANA_PEN_SigScale},
   		{'Product-Name', "SigScale OCS"},
   		{'Firmware-Revision', Version},
   		{'Supported-Vendor-Id', [?IANA_PEN_3GPP]},
  
positive.code: %% @hidden
  service_options(Options) ->
  	{ok, Vsn} = application:get_key(vsn),
  	{ok, NrfUri} = application:get_env(ocs, nrf_uri),
  	Version = list_to_integer([C || C <- Vsn, C /= $.]),
  	{ok, Hostname} = inet:gethostname(),
  	Options1 = case lists:keymember('Origin-Host', 1, Options) of
  
negative.code: 		{application, [{alias, ?BASE_APPLICATION},
  				{dictionary, ?BASE_APPLICATION_DICT},
  				{module, ?BASE_APPLICATION_CALLBACK},
  				{request_errors, callback}]},
  		{application, [{alias, ?Gx_APPLICATION},
  				{dictionary, ?Gx_APPLICATION_DICT},
  