Mobile phone commercially available handheld mobile phone. From 1983 to 2014, worldwide mobile phone subscriptions grew to over seven billion—enough to provide one for every person on Earth. In first quarter of 2016, the top smartphone developers worldwide were Samsung, Apple, and Huawei, with smartphone sales represented 78 percent of total mobile phone sales. For feature phones (or "dumbphones") , the largest were Samsung, Nokia, and Alcatel. A handheld mobile radio telephone service was envisioned in the early stages of radio engineering. In 1917, Finnish inventor Eric Tigerstedt filed a patent for a "pocket-size folding telephone with a very thin carbon microphone".
Mobile phone away from heat. Mobile phones require a small microchip called a Subscriber Identity Module or SIM card, in order to function. The SIM card is approximately the size of a small postage stamp and is usually placed underneath the battery in the rear of the unit. The SIM securely stores the service-subscriber key (IMSI) and the K used to identify and authenticate the user of the mobile phone. The SIM card allows users to change phones by simply removing the SIM card from one mobile phone and inserting it into another mobile phone or broadband telephony device, provided that this