TRANSACTION_TYPE_UID	END_OF_CALL	        SUBSCRIBER_UID	        BALANCE
79001	                2014/04/26 13:47	606094135		2147483648
79001	                2014/04/26 13:51	606094135		4294967296
79001	                2014/04/30 16:53	606096826		104857600
79001	                2014/04/22 12:49	606104927		524288000
79013	                2014/04/10 14:59	798190099		61200812
79013	                2014/04/22 14:43	818888488		1888107861

  SELECT t.transaction_type_uid,
         t.end_of_call,
         t.subscriber_uid,
         t.balance
    FROM test t
   WHERE t.end_of_call =
            (SELECT MAX (t1.end_of_call)                                     --> latest value
               FROM test t1
              WHERE t1.transaction_type_uid = t.transaction_type_uid         --> per transaction type
                    AND t1.subscriber_uid = t.subscriber_uid)                --> per subscriber
ORDER BY t.transaction_type_uid, t.subscriber_uid, t.end_of_call;