on in a wireless network. Similar to wireline networks, billing records are collected to compute the utilization. Convergent billing: In convergent billing all service charges associated with a user or user group is integrated onto a single invoice. This will give a unified view of all the services provided to that customer. Services in a convergent bill can account for voice, data, IPTV (Internet Protocol Television), internet, Fundamentals of EMS, NMS and OSS/BSS Video-On-Demand (VOD), and many more services that a customer is using from the service provider. IP billing: The billing for IP-based services like VoIP (Voice over Internet Protocol). In IP billing it is usually the content that determines the bill amount rather than the distance between the origin and destination as in tra- ditional billing methods. This is because IP distance will not be a key factor and it will be parameters like quality of service and security level that deter- mines the tariff to be imposed on the service subscribed by the customer. Interconnect billing: Services can span across multiple service providers. For example, a simple phone call between two people can involve two ser- vice providers, when each of them is serviced by a different service provider. Outgoing call charges are imposed by one service provider at the call origi- nating end and incoming call charges are imposed by another service pro- vider at the call terminating end. This setup connecting the network from different service providers/operators requires some kind of billing mecha- nism to monitor the actual amount of data (sent and received). It is known as interconnect. Some of the billing models are: Volume-based billing: Here the bill is calculated based on the volume of data (total size). An internet service provider charging the customer based on the volume of data upload and download is an example of using volume-based billing. Duration-based billing: In this billing, time is the determining factor. An Internet service provider charging the customer based