Mobile Telephone Switching Office

The Mobile Telephone Switching Office (MTSO) is the mobile equivalent of a PSTN Central 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 Mobile Telephone Switching Office (MTSO) is the mobile equivalent of a PSTN Central 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 (with the help of its CBM/SDM), etc. It also provides resources needed to efficiently serve a mobile subscriber such as registration, authentication, location updating and call routing. Its subordinate BSC/RNC are responsible for assigning frequencies to each call, reassigning frequencies for handoffs, controlling handoffs so a mobile phone leaving one cell (formally known as BTS)'s coverage area, can be switched automatically to a channel in the next cell.