A mobile phone is a portable telephone that can make and receive calls over a radio frequency link while the user is moving within a telephone service area. The first handheld mobile phone was demonstrated by John F. Mitchell and Martin Cooper of Motorola in 1973, using a handset weighing 2 kilograms (4.4 lbs). In 1983, the DynaTAC 8000x was the first commercially available handheld mobile phone. From 1983 to 2014, worldwide mobile phone subscriptions grew to over seven billion, penetrating 100% of the global population and reaching even the bottom of the economic pyramid. In first quarter of 2016, the top smartphone manufacturers were Samsung, Apple, and Huawei and smartphone sales represented 78 percent of total mobile phone sales.