less protocol because packets arrive at their destination independently from various routes without sequence numbers. There is no assurance that all of the packets for a particular message arrive. UDP is suited for applications such as database lookups, voice, and short messages. UMTS (Universal Mobile Tele-communications System) A European standard for 3G mobile wireless networks that GSM networks generally use when they are upgraded. WCDMA is a UMTS technology. UMTS TDD (Universal Mobile Telecommunications System/Time-Division Duplexing) A high-speed wireless technology used for 3G cellular and broadband wireless access to the Internet. It is also referred to as TD-CDMA. It uses the same channel for sending and receiving, with small time slots to separate the sending and receiving streams rather than the larger guard band used in other 3G technologies. www.TechnicalPDF.com UNE (Unbundled Network Element) Parts of the incumbent local telephone company infrastructure required to lease out to other local exchange carriers. Examples of UNEs are the copper lines to customers' premises. Many UNE requirements have been eliminated. unicasting The transmission of one message from a single point to another point. This is also referred to as point-to-point communications. unified messaging Computing platform that contains voicemail, facsimile, e-mail, and sometimes video mail on a single system. Users can access all of these services from their computer inbox. unlicensed spectrum Governments specify portions of the airwaves for unlicensed services at no charge to companies; 802.11 services are an example. Most governments issue certification, signal-spreading, and power-limitation rules to protect adjacent licensed spectrum bands from harmful interference from transmissions within the unlicensed spectrum. Uplink (UL) On broadband and mobile networks, the uplink carries traffic from the customer to the carrier's equipment. URL (Universal Resource Locator) An address on the World Wide Web. The address is made up of strings 