 SO on. Now, how complex would the bill be for the case when the segregation of charges for a package of services is provided in a single bill. The billing information should be presented to the customer in a format that is easy to understand and helpdesk/online/call support should be offered to customers for clarifying bill related queries. Multimode, multipayment, and multiparty options: In multimode billing, the billing system must be capable of handling "real-time or nonreal-time" billing of "single or batch" billing records. Multipayment option, also known as unified accounting gives the customer the ability to do payment using postpay, prepay, nowpay, or combination of these payment options. The mul- tiparty settlement option gives a customer the flexibility to settle multiple bills related to the customer or multiple bills incurred by multiple parties. For example, all bills associated to different members in a family can be linked to a single payee. This leads to ease in payment of bills. It should be kept in mind that the billing system in service provider space should have the required capabilities to offer multipayment and multiparty options to the customer. Billing system should have carrier-grade performance: Current billing systems have to support complex billing models. Even when advanced functionalities are offered, the billing system should still be scalable. An increased number of billing records should not affect the performance of the system. The bill- ing system should provide enough abstraction of information to make it easy for the operator to work on the system. Availability is the key requirement of a billing system, as a few seconds of discontinuity in billing can result in a major financial loss to the service provider. The billing module interacts with many other support system modules (see Figure 20.13). The main interactions at the business level happen with customer care and marketing and sales modules. At the service level, the interaction is with Customer Marketing and sales Billi