 Information in the database is accessed by the rating engine to rate the calls. The rating engine will apply the payment rules on the transactions. Discounts and promoting can also be applied. 5. The information from a rating engine is sent to the billing system for sending the invoice. Any bill related settlements can be done by the billing system. 6. Invoices prepared by the billing system are sent to the customer as post, e-mail, or uploaded to a secure Web page. Most service providers allow the customer to register in the service provider Web site and give them the capa- bility to securely access and pay their bills through the Internet. Some of the essential requirements in billing are: Multiple rating techniques: In a competitive market it is essential to pro- vide the customer with different rating plans. Customers can be segmented based on: - Geography: The parameters used for this segment include region, popula- tion size, density, and climate. - Demography: The parameters used for this segment include age, family size, income, gender, occupation, education, and social class. - Psychograph: The parameters used for this segment include lifestyle and personality. - Behavior: The parameters used for this segment include evaluation of benefits, analysis of usage rate, and attitude toward a specific product. Different customer segments have different needs and a single rating for all customers will not satisfy customer needs. Service providers are coming up with innovative plans that best satisfy the customer segments. Convergent billing: There would be multiple services from a service provider that a customer would be using. The customer might opt to use broadband internet, IPTV, Call Service, and On-Demand services from a single service provider. These services will be offered as a package by the service provider for a rate that would be less compared to the amount the customer has to pay when these services are subscribed on an individual basis. Rather than separate bills for individual services, the cust