From GSM to LTE: An Introduction to Mobile Networks and Mobile Broadband

1.11 The Intelligent Network Subsystem and CAMEL

All components that have been described in this chapter are mandatory elements for the operation of a mobile network. Mobile operators, however, usually offer additional services beyond simple postpaid voice services for which additional logic and databases are necessary in the network. Here are a few examples:

• Location-based services (LBS) are offered by most network operators in Germany in different variations. One LBS example is to offer cheaper phone calls to fixed-line phones in the area in which the mobile subscriber is currently located. To be able to apply the correct tariff for the call, the LBS service in the network checks if the current location of the subscriber and the dialed number are in the same geographical area. If so, additional information is attached to the billing record so that the billing system can later calculate the correct price for the call.
• Prepaid services have become very popular in many countries since their introduction in the mid-1990s. Instead of receiving a bill once a month, a prepaid subscriber has an account with the network operator, which is funded in advance with a certain amount of money determined by the subscriber. The amount on the account can then be used for phone calls and other services. During every call, the account is continually charged. If the account runs out of credit, the connection is interrupted. Furthermore, prepaid systems are also connected to the SMSC, the multimedia ...