sure that a COTS product will interoperate as expected with an exist- ing product. NGOSS based applications should allow solutions to be rapidly implemented through integration of off-the-shelf software components. ATCA (Advanced Telecommunications Computing Architecture) is a modular com- puting architecture from PICMG for COTS telecom hardware development. Let us conclude the discussion by mentioning some of the key players that offer assurance solutions. After acquiring Tivoli Systems Inc. and Micromuse, IBM has emerged as the market leader in offering a variety of assurance solutions. HP Openview products of Hewlett-Packard (HP) can manage and monitor a wide vari- ety of network elements used in data, access, and transport network. Computer Associates have a suite of solutions for management of application servers. TTI Telecom offers OSS service assurance solutions suited for fixed, mobile, and cable networks. Telcordia is another OSS solutions provider worth mentioning in the market leaders for assurance solutions. 20.4 Billing Process Billing corresponds to the processes in service provider space for getting revenue from the customer for the services consumed. The service used by the customer is metered for generating the bill. There is a rate associated with the service plan Fundamentals of EMS, NMS and OSS/BSS Customer Invoicing Collection Discounts Service Rating incentives Billing record Billing data Network collection analysis Figure 20.11 Billing process. selected by the customer. This rate is applied on the service consumed to compute the customer amount due to the service provider at the end of a billing cycle. The billing system should allow easy management of customer accounts. A central- ized repository that maintains a record of customer payments will be queried and updated by the billing system. The three main processes in billing are (see Figure 20.11): 1. Invoicing and collection: This is a customer level process. An invoice is gener- ated for the customer with information on the bill amount 