anchor.diff:  			Subscriber, Balance, ResultCode),
   	{reply, Reply, State}.
   
  +-spec decrement_balance(Subscriber, Usage) -> Result
  +	when
  +		Subscriber :: string() | binary(),
  +		Usage :: non_neg_integer(),
  +		Result :: {ok, NewBalance, DiscFlag} | {error, Reason },
  +		NewBalance :: integer(),
  +		DiscFlag :: boolean(),
  +		Reason :: not_found | term().
  +%% @doc Decrements subscriber's current balance
  +decrement_balance(Subscriber, Usage) when is_list(Subscriber) ->
  +	decrement_balance(list_to_binary(Subscriber), Usage);
  +decrement_balance(Subscriber, Usage) when is_binary(Subscriber),
  +		Usage >= 0 ->
  +	F = fun() ->
  +		case mnesia:read(subscriber, Subscriber, write) of
  +			[#subscriber{balance = Balance, disconnect = Flag} = Entry] ->
  +				NewBalance = Balance - Usage,
  +				NewEntry = Entry#subscriber{balance = NewBalance},
  +				mnesia:write(subscriber, NewEntry, write),
  +				{NewBalance, Flag};
  +			[] ->
  +				throw(not_found)
  +		end
  +	end,
  +	case mnesia:transaction(F) of
  +		{atomic, {NewBalance, Flag}} ->
  +			{ok, NewBalance, Flag};
  +		{aborted, {throw, Reason}} ->
  +			{error, Reason};
  +		{aborted, Reason} ->
  +			error_logger:error_report(["Failed to decrement balance",
  +					{error, Reason}, {subscriber, Subscriber}]),
  +			{error, Reason}
  +end.
  +
  
positive.code: 			{ok, Password, _, Balance, true} ->
  				case ocs:authorize(Subscriber, Password) of
  					{ok, _, _} ->
  						request1(RequestType, SId, RequestNum, Subscriber, Balance, OHost, ORealm, State);
  					{error, _} ->
  						send_error(SId, Subscriber, Balance, ?'DIAMETER_BASE_RESULT-CODE_AUTHORIZATION_REJECTED',
  								OHost, ORealm, ?CC_APPLICATION_ID, RequestType,
  
negative.code: 
  %% @hidden
  request1(?'DIAMETER_CC_APP_CC-REQUEST-TYPE_INITIAL_REQUEST' = RequestType,
  		_Request, SId, RequestNum, Subscriber, Balance, OHost, ORealm, State) ->
  	send_answer(SId, Subscriber, Balance, ?'DIAMETER_BASE_RESULT-CODE_SUCCESS',
  			OHost, ORealm, ?CC_APPLICATION_ID, RequestType,
  			RequestNum, State);
  request1(?'DIAMETER_CC_APP_CC-REQUEST-TYPE_UPDATE_REQUEST' = RequestType,
  		Request, SId, RequestNum, Subscriber, Balance, OHost, ORealm, State) ->
  	try
  		UsedUnits = Request#'diameter_cc_app_CCR'.'Used-Service-Unit',
  		#'diameter_cc_app_Used-Service-Unit'{'CC-Total-Octets' = Total,
  				'CC-Input-Octets' = In, 'CC-Output-Octets' = Out} = UsedUnits,
  		Usage = case Total of
  			Total when is_integer(Total) ->
  				Total;
  			_ ->
  				case {In, Out} of
  					{In, Out} when is_integer(In), is_integer(Out) ->
  						In + Out;
  					_ ->
  						throw(no_diameter_accounting_usage_information)
  				end
  		end,
  		case decrement_balance(Subscriber, Usage) of
  			{ok, OverUsed, false} when OverUsed =< 0 ->
  				send_answer(SId, Subscriber, Balance, ?'DIAMETER_BASE_RESULT-CODE_SUCCESS',
  						OHost, ORealm, ?CC_APPLICATION_ID, RequestType,
  						RequestNum, State);
  			{ok, _SufficientBalance, _Flags} ->
  				send_answer(SId, Subscriber, Balance, ?'DIAMETER_BASE_RESULT-CODE_SUCCESS',
  						OHost, ORealm, ?CC_APPLICATION_ID, RequestType,
  						RequestNum, State);
  			{error, not_found} ->
  				error_logger:warning_report(["diameter accounting subscriber not found",
  						{module, ?MODULE}, {subscriber, Subscriber},
  						{origin_host, OHost}]),
  				send_error(SId, Subscriber, Balance, ?'DIAMETER_BASE_RESULT-CODE_UNABLE_TO_COMPLY',
  						OHost, ORealm, ?CC_APPLICATION_ID, RequestType,
  						RequestNum, State)
  		end
  	catch
  		_:_ ->
  			send_error(SId, Subscriber, Balance, ?'DIAMETER_BASE_RESULT-CODE_UNABLE_TO_COMPLY',
  					OHost, ORealm, ?CC_APPLICATION_ID, RequestType,
  					RequestNum, State)
  	end;
  request1(?'DIAMETER_CC_APP_CC-REQUEST-TYPE_TERMINATION_REQUEST' = RequestType,
  		_Request, SId, RequestNum, Subscriber, Balance, OHost, ORealm, State) ->
  	F = fun() ->
  		case mnesia:read(subscriber, Subscriber, write) of
  			[#subscriber{disconnect = false} = Entry] ->
  