All the user equipment such as a cell phone, SIM card…etc. and software needed for communication with a GSM network. The four main components in GSM mobile stations are:
Mobile termination which handles functions such as radio transmission, speech encoding/decoding, error detection/correction, and access to the SIM.
Terminal equipment is any device connected to the mobile station which offers services to the user, such as a mobile phone or other mobile device.
Terminal adapter which provides access to the mobile termination (MT).
SIM card or subscriber identity module which is a removable memory circuit that stores the subscriber identification token and authentication protocol.