ay that the power-per-unit bandwidth is constant. Also called white noise. UNII (Unlicensed National Information Infrastructure) Unlicensed radio bands that operate at 5.2GHz. Universal Service Fund A U.S. government program that provides subsidies for telephone service in areas that might otherwise have difficulties obtaining economical telephone service, particularly low-income areas and rural areas. UNIX A multiuser, open operating system developed by Bell Laboratories. unlicensed bands Radio bands that can be used to provide broadband access, without the need for obtaining a license. Networks that use unlicensed bands have a range of about 35 miles (55 km) and offer throughput from 128Kbps to 10Mbps over shared media. unshielded cable A cable in which the signal-carrying wire or circuit is not shielded to keep out electromagnetic noise that can potentially damage the data stream. upload To send data from a local system to a remote system. UPS (uninterruptible power supply) A device that usually includes an inverter, drawing its power from batteries, which generates an extremely well-behaved AC power signal for a PBX or other equipment. If a particularly heavy demand is anticipated, the system can be coupled with an auxiliary generator that is started when commercial power is interrupted. upstream The direction of transmission flow away from a user. UPT (Universal Personal Telephony) An ITU-R standard for the provision of personal mobility across many different kinds of fixed and mobile networks. UTP (unshielded twisted-pair) A twisted-pair cable in which the two insulated wires that twist around each other are not surrounded by additional insulation. UWB (Ultra-Wideband) A technique based on transmitting very-short-duration pulses, where the occupied bandwidth is very large, allowing for very high data rates. UWB is used in both wired and wireless PANs to relay data from a host device to other devices up to 30 feet (10 m) away. UWC (Universal Wireless Communications) Also called ANSI-136, a wireless standard 