sion of local telephone service is deregulated (as is the goal in Europe), a subscriber is able to choose a network operator for local calls by dialing a local operator prefix in front of the subscriber number. 2.5.5 Operator Numbers As the telecommunications business is deregulated, new service providers are beginning to enter on the market. Then in addition to the numbers just described, a subscriber will need to dial additional digits to select a service provider (network operator). As explained earlier, a subscriber may choose a service provider for local calls, long-distance calls, and international calls. The national telecommunications authority defines the operator numbers The Telecommunications Network: An Overview used. The national telecommunications authority also defines how calls dialed without an operator number are charged. If the subscriber does not specify the international and long-distance network operators by operator prefix, the network is chosen randomly or according to other rules specified by the national telecommunications authority. The creation of real competi- tion in fixed telecommunications service provision has been successful in many countries. One problem with this situation is that additional dialing of operator prefixes at all levels is required, and another is that the fees for fixed telephone service are too low to make subscribers interested in taking the time to choose a service provider. For business users, for which monitoring the costs of telecommunica- tions is essential, competition will certainly reduce those costs. To avoid the problem of additional dialing, a business or residential subscriber may make a service agreement with one of the network operators for local, long- distance, and international calls. 2.6 Switching and Signaling To build the requested connection from one subscriber to another, the net- work has switching equipment that selects the required connection. These switching systems are called exchanges. The subscriber identifies the required connectio