istical multiplexing Used in televisions, radios, and set-top boxes because capacity is unused when the device to filter out all channels (frequencies) except is not transmitting. the particular one at the frequency the tuner is designed to accept. The tuner then adapts topology the frequency to ones compatible with the TV The geometric shape of the physical connec- or radio. Newer set-top boxes are equipped tion of the lines in a network-or, the "view with multiple tuners SO that one channel can from the top"-which is the shape of the be recorded while another is being viewed. Glossary tunneling UNE (Unbundled Network Element) A method of securely transferring data Parts of the incumbent local telephone com- between sites connected by networks such pany infrastructure required to lease out as a VPN, the Internet, an intranet, or an to other local exchange carriers. Examples extranet. Tunneling puts a new header in of UNEs are the copper lines to customers' front of the data. This is a way of separating premises. Many UNE requirements have data from multiple companies using the same been eliminated. network. unicasting UDP (User Datagram Protocol) The transmission of one message from a Part of the TCP/IP suite of protocols. UDP single point to another point. This is also has less overhead because it does not have referred to as point-to-point communications. bits with packet numbers and acknowledg- ments. UDP is considered a connectionless unified messaging protocol because packets arrive at their des- Computing platform that contains voicemail, tination independently from various routes facsimile, e-mail, and sometimes video mail without sequence numbers. There is no assur- on a single system. Users can access all of ance that all of the packets for a particular these services from their computer inbox. message arrive. UDP is suited for applica- tions such as database lookups, voice, and unlicensed spectrum short messages. Governments specify portions of the air- waves for unlicensed services at no charge to UMT