Mobile Telephone Switching Office

The MTSO contains the switching equipment or Mobile Switching Center (MSC) for routing mobile phone calls. It also contains the equipment for controlling the cell sites that are connected to the MSC.

          The systems in the MTSO are the heart of a cellular system. It is responsible for interconnecting calls with the local and long distance landline telephone companies, compiling billing information. It also provides resources needed to efficiently serve a mobile subscriber such as registration, authentication, location updating and call routing. All cellular systems have at least one MTSO which will contain at least one MSC. The MSC is responsible for switching calls to mobile units as well as to the local telephone system, recording billing data and processing data from the cell site controllers.

          The MSC is connected to a close telephone exchange by a trunk group. This provides an interface to the Public Switched Telephone Network (PSTN). It also provides connectivity to the PSTN. The region to be served by a Cellular Geographic Serving Area (CGSA) is split into geographic cells. These cells are ideally hexagonal in shape and they are initially laid out with their centers about 4 to 8 miles apart from each other.