 DS-0 channels on a T-3 facility; DS-3 is a 44.736Mbps digital signal carried over 672 DS-0 channels on a T-3 facility; and DS-4 is a 274.176Mbps digital signal carried over 4,032 DS-0 channels on a T-4 facility. DSCP (DiffServ Code Point) A field in the packets transported over DiffServ networks that classifies the packets according to priority. DiffServ uses a DSCP to select the per-hop behavior of the packet at each DiffServ-capable node. Glossary DSG (DOCSIS Set-top Gateway) DSG (DOCSIS Set-top Gateway) An extension to the DOCSIS standards that gives opera- tors a standard method to deliver out-of-band data, such as channel lineups and program guides, and more advanced streaming applications via a DOCSIS channel to the digital cable set-top box. (digital speech interpolation) A system of digitized speech in which the speech can be cut into slices such that no bits are transmitted when a person is silent. As soon as speech begins, bits flow again. DSL (Digital Subscriber Line) A family of broadband technologies that use sophisticated modulation schemes to pack data onto copper wires. They are sometimes referred to as last-mile tech- nologies because they are used only for connections from a telephone switching station to a home office, not between switching stations. The family of technologies is often referred to as xDSL. DSL bonding The process of linking several DSL lines to configure bandwidth between the T-1/T-3 and E-1/E-3 rates. DSLAM (DSL access multiplexer) A device at a phone company's central location that links many customer DSL connections to a single high-speed ATM line. DSP (digital signal processing) The study of signals in a digital representation and the processing methods for these signals. DSSS (Direct Sequence Spread Spectrum) A spread spectrum technique in which each data bit is converted to a series of 10 to 144 transmitted bits or chips. DSU (data service unit) A synchronous serial data interface that buffers and controls the flow of data between a digital terminal and the CSU attached 