A mobile phone (also known as a cell phone or cellular phone) is a telephone which can make and receive calls over a radio frequency carrier while the user is moving within a telephone service area. The radio frequency link establishes a connection to the switching systems of a mobile phone operator, which provides access to the public switched telephone network (PSTN). A modern mobile telephone service uses a cellular network architecture. In addition to telephony, modern mobile phones support a variety of other services, such astext messaging, MMS, email, Internet access, short-range wireless communications (infrared, Bluetooth), business applications, gaming, and photography. Mobile phones which offer these and more general computing capabilities are referred to as smartphones.