Cellular handsets operate by radio, and depending upon the services required may have 5 separate radio systems. Great care is needed in handset design to prevent radios from interfering with each other or RF energy at intermediate frequencies, reducing receiver sensitivity. For example, cellular communications has both receiving and transmitting functions using the Long Term Evolution, or LTE, standard. In the USA this may operate in nine different frequency bands between 700 and 2600 MHz. Bluetooth Low Energy, or BLE, used for wireless hands-free headsets, ear pieces, or connection to vehicle audio systems, has both receiving and transmitting functions at approximately 2.4 GHz. For WiFi service the handset has both receiving and transmitting functions at either 2.4 or 5.0 GHz. GPS, used for location and mapping services, is a receive only channel at approximately 1.5 GHz. Finally, NFC enabled handsets have both receiving and transmitting functions at 13.56 MHz.