A SIM card for a phone has a first memory partition on which a phone user identity and phone network access data are stored. A service usage monitoring application is stored in a memory. The service usage monitoring application (a) logs information about a service used via the phone, (b) creates a service usage record for the service activity based on the information, (c) stores the service usage record in a buffer, (d) creates a reporting message containing at least one service usage data record, (e) sends the reporting message to a remote server at a preset interval based on a triggered event, and (f) purges the at least one service usage record from the buffer upon successful transmission of the reporting message.