A mobile phone is a portable phone that can make and receive calls through a radio frequency link while the user is moving within a telephone service area. The radiofrequency link establishes a connection with the switching systems of a mobile telephone operator, which provides access to the public switched telephone network (PSTN). Modern mobile phone services use a cellular network architecture and, therefore, mobile phones are often also called cell phones or cell phones. In addition to telephony, mobile phones in the 2000s support a variety of other services such as text messaging, MMS, e-mail, Internet access, short-range wireless communications (infrared, Bluetooth), enterprise applications, video games and Digital photography. Mobile phones that offer only those capabilities are known as feature phones; mobile phones that offer very advanced computing capabilities are known as smartphones.
The first handheld mobile phone was shown by John F. Mitchell and Martin Cooper of Motorola in 1973, using a headset weighing c. 2 kilograms (4.4 pounds). In 1983, the DynaTAC 8000x was the first commercially available handheld mobile phone. From 1983 to 2014, subscriptions to mobile phones worldwide grew to more than seven billion, penetrating 100% of the world's population and reaching the bottom of the economic pyramid. In the first quarter of 2016, the leading smartphone manufacturers were Samsung, Apple and Huawei (and "martphone sales accounted for 78 percent of total mobile phone sales").
Common components found on all phones are:
• A battery, which provides the power source for phone functions.
• An input mechanism to allow the user to interact with the phone. These are a keypad for feature phones and touch screens for most smartphones.
• A screen that echoes the user's writing shows text messages, contacts and more.
• Basic mobile phone services to allow users to make calls and send text messages.
• All GSM phones use a SIM card to allow an account to be exchanged between devices. Some CDMA devices also have a similar card called R-UIM.
• Individual GSM, WCDMA, iDEN and some satellite telephony devices are uniquely identified by an International Mobile Equipment Identity (IMEI) number.
Low-end mobile phones are often referred to as feature phones and offer basic telephony. Phones with more advanced computing capabilities through the use of native software applications are known as smartphones.
Sound
In sound, smart phones and feature phones vary little. Some audio quality enhancement features, such as Voice over LTE and HD Voice, have appeared and are often available on newer smartphones. Sound quality can continue to be a problem due to the design of the phone, the quality of the cellular network and the compression algorithms used in long distance calls. Audio quality can be improved through a VoIP application over WiFi. Cell phones have small speakers so the user can use a speakerphone function and talk to a person on the phone without having to hold their ear. Small speakers can also be used to listen to digital music or voice audio files or watch videos with an audio component without having the phone close to the ear.
SIM card
GSM function phones require a small microchip called a Subscriber Identity Module or SIM card to operate. The SIM card is about the size of a small postage stamp and is usually placed under the battery at the back of the unit. The SIM card securely stores the service subscriber key (IMSI) and the Ki used to identify and authenticate the mobile telephone user. The SIM card allows users to switch phones by simply removing the SIM card from a mobile phone and inserting it into another mobile phone or broadband telephony device, as long as this is not avoided by a SIM lock. The first SIM card was made in 1991 by Munich-based smart card maker Giesecke & Devrient for the Finnish wireless network operator Radiolinja.
A hybrid mobile phone can hold up to four SIM cards. SIM and R-UIM cards can be mixed together to allow access to GSM and CDMA networks. As of 2010, these phones became popular in emerging markets, and this was attributed to the desire to obtain the lowest rate of calls on the network.