Mobile phone features (2.0), dual line support, infrared, Bluetooth (2.0) and WiFi connectivity, NFC, instant messaging, Internet e-mail and browsing and serving as a wireless modem. The first smartphone was the Nokia 9000 Communicator in 1996 which added PDA functionality to the basic mobile phone at the time. As miniaturization and increased processing power of microchips has enabled ever more features to be added to phones, the concept of the smartphone has evolved, and what was a high-end smartphone five years ago, is a standard phone today. Several phone series have been introduced to address a given market segment, such as the RIM
Mobile phone signal which may exist even in locations in which a wireless carrier offers coverage, due to limitations in cellular network architecture (the locations of antennas), limited network density, interference with other mobile sites, and topography. Since cell phones rely on radio waves, which travel though the air and are easily attenuated (particularly at higher frequencies), mobile phones may be unreliable at times. Like other radio transmissions, mobile phone calls can be interrupted by large buildings, terrain, trees, or other objects between the phone and the nearest base. Cellular network providers work continually to improve and upgrade their networks in order to