BSS is the base station subsystem is the section of the traditional cellular network which is responsible for handling and management of all user data traffic and signaling between a mobile phone and the NSS (Network switching subsystem). It carries out transcoding of speech signals, allocation of radio channels to mobile phones, paging, transmission, and reception over the air interface. It may perform other tasks related to the network. BSS comprises two units BTS ( Base Transceiver Station) and BSC (Base station controller). BTS contains equipment for transmitting and receiving radio signals, equipment for encrypting and decrypting communications with BSC. A BTS is controlled by the parent BSC via a base station controller function. The functions of BTS vary depending upon cellular technology. The BSC is the intelligence behind the BTS. A BSC can control tens to hundreds of BTS. the BSC’s are controlled by the MSC (Mobile switching center).