ent standardizing forums with work groups specifically for customer centric management. 19.4 What Do Support Systems Offer? The support systems handle the customer, the services that are offered to the cus- tomer and the resources that offer the services (see Figure 19.1). Managing the customer is a part of the business support while billing is a business operation of the service management that finally applies to the customer. So in most scenarios the three entities that influence the support systems are the resource/infrastructure service, and customer. 19.4.1 Support Systems to Manage the Customers The main part of customer management is to manage the customer account. This account has details on the customer contact, information on the services the cus- tomer has prescribed, and the contracts between the service provider and customer. Tracking on customer raised issues and the usage of the service is all mapped to OSS/BSS Manage service and business Infrastructure Deliver services Customer Figure 19.1 Holistic view of support systems. Fundamentals of EMS, NMS and OSS/BSS this account. In most cases a unique identification number is associated to each customer as part of the account and used as reference in all transactions associated to the customer across the different modules in support systems. Another aspect in customer management that needs to have a defined process is the sales process. First the sales process should ensure that the customer requirements are satisfied with the specific service offering. The different phases in the sales lifecycle that affect the customer like the ordering process, the change of service or add-ons to the service, and even termination of service needs to be managed. It could be a bundled OSS/ BSS solution that takes care of customer management or stand alone modules like an order management system. Customer billing is also a key aspect of customer management that forms the mainstream activity in business support system. This will include determining how much the customer 