Disclosed is a species of control-message intercept method which includes a passive monitoring approach whereby the relevant control packets are inspected for the purpose of providing additional information for the purpose of facilitating the operation of some primary or ‘master’ Internet Protocol (IP) charging/rating middleware platform/gateway system (intended to equip network operators with the ability to rate and bill IP traffic), and secondly, an invasive technique whereby control (GTP-C) messages are injected for the purpose of altering the state of a given data session in an more aggressive fashion (e.g. to drop a data session when the subscriber runs out of money in his/her prepaid account).