A method of determining whether a user has complied with a service level agreement (SLA) with a network operator, comprising collecting a set of data values representative of the user's service usage and comparing the set of data values to the service level agreement. The data values collected provide the operator with sufficient information so that it can determine whether a SLA is being complied with and to plan provision of network services. A method of monitoring a user's usage of a network service and a service usage indicator is also disclosed.