S (Universal Mobile Telecommu- companies; 802.11 services are an example. nications System) Most governments issue certification, signal- A European standard for 3G mobile wire- spreading, and power-limitation rules to pro- less networks that GSM networks generally tect adjacent licensed spectrum bands from use when they are upgraded. WCDMA is a harmful interference from transmissions UMTS technology. within the unlicensed spectrum. UMTS TDD (Universal Mobile Tele- Uplink (UL) communications System/Time- On broadband and mobile networks, the up- Division Duplexing) link carries traffic from the customer to the A high-speed wireless technology used for carrier's equipment. 3G cellular and broadband wireless access to the Internet. It is also referred to as TD- URL (Universal Resource Locator) CDMA. It uses the same channel for sending An address on the World Wide Web. The and receiving, with small time slots to sepa- address is made up of strings of data that rate the sending and receiving streams rather identify the server, the folder location, and than the larger guard band used in other 3G other information indicating the location of technologies. information on the Internet. Glossary USF (Universal Service Fund) "virtual" networks that act as if they were Used to fulfill the commitment made by separate LANs. the United States government to affordable universal telephone service to all residen- VolP (Voice over Internet Protocol) tial consumers. The Telecommunications The process of sending voice traffic in pack- Act of 1996 expanded universal service to ets on IP-based data networks. VoIP digitizes rural healthcare organizations, libraries, and analog voice, compresses it, and puts it into educational institutions for Internet access, packets at the sending end. The receiving inside wiring, and computers. The library and end does the reverse. Unlike circuit switch- educational subsidies are a part of universal ing, no path is saved for the duration of the service known as the e-rate. Every interstate voice ses