1. A method for supporting reauthorization functionality in a CAMEL network, the method comprising: receiving at a Service Capability Interaction Manager (SCIM) an Initial Detection Point/Initial Detection Point General Packet Radio Service (InitialDP/InitialDPGPRS) request over the CAMEL network from a mobile switching center (MSC) related to a requested service; sending an initial Credit Control Request (CCR) from the SCIM to an Online Charging System (OCS) establishing a session for the requested service; receiving a Credit Control Answer (CCA) at the SCIM from the OCS granting an initial granted number of units; calculating with the SCIM an initial allocation of units comprising some of the initial granted number of units; sending an ApplyCharging/ApplyChargingGPRS message from the SCIM to the MSC with the initial allocation of units; receiving, in response to a top-up transaction, a Re-Authorization Request (RAR) message at the SCIM from the OCS; sending a Re-Authorization Response (RAA) message from the SCIM to the OCS; sending a CCR update message from the SCIM to the OCS charging the units of the a used units counter in the SCIM to the OCS; receiving a CCA at the SCIM from the OCS granting a new granted number of units; and resetting the used units counter in the SCIM to zero; whereby, the new granted number of units recognizes units made available by the top-up transaction and whereby the SCIM is enabled to make a new allocation of units comprising some of the new granted number of units to the MSC over the CAMEL network thereby allowing the MSC to continue to provide the requested service in the same session.