A digital cross-connect system (DCS) is a piece of circuit-switched network equipment, typically used in telephone networks, that allows lower-level TDM bit streams, such as DS0 bit steams, to be rearranged and interconnected among higher-level TDM signals, such as DS1 bit streams. DCS units are available that operate on both older T-carrier/E-carrier bit streams, as well as newer SONET/SDH bit streams. To meet Wikipedias quality standards, this article or section may require cleanup. ... Time-division multiplexing (TDM) is a type of digital multiplexing in which two or more apparently simultaneous channels are derived from a given frequency spectrum, i. ... A bitstream or bit stream is a time series of bits. ... In T-carrier systems Digital signal 0 (DS0) is a basic digital signaling rate of 64 kb/s, corresponding to the capacity of one voice-frequency-equivalent channel. ... Digital signal 1 (DS1, also known as a T1) is a T-carrier signaling scheme devised by Bell Labs. ... Two Network Interface Units, one with a single card, the other with two In telecommunications, T-carrier is the generic designator for any of several digitally multiplexed telecommunications carrier systems originally developed by Bell Labs and used in North America and Japan. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... The Synchronous optical network, commonly known as SONET, is a standard for communicating digital information using lasers or light emitting diodes (LEDs) over optical fiber as defined by GR-253-CORE from Telcordia. ...

DCS devices can be used for "grooming" telecommunications traffic, switching traffic from one circuit to another in the event of a network failure, supporting automated provisioning, and other applications. Having a DCS in a circuit-switched network provides important flexibility that can otherwise only be obtained at higher cost using manual "DSX" cross-connect patch panels. Traffic grooming is the process of taking telecommunications traffic and sorting it into the most efficient arrangement possible. ... A patch panel is a panel, typically rack mounted, that may house cable connections. ...

It is important to realize that while DCS devices "switch" traffic, they are not packet switches—they switch circuits, not packets, and the circuit arrangements they are used to manage tend to persist over very long time spans, typically months or longer, as compared to packet switches, which can route every packet differently, and operate on micro- or millisecond time spans. In computer networking and telecommunications, packet switching is a communications paradigm in which packets (messages or fragments of messages) are individually routed between nodes, with no previously established communication path. ...

DCS units are also sometimes colloquially called "DACS" units, after a proprietary brand name of DCS units created and sold by AT&T's Western Electric division, now Lucent. A genericized trademark (Commonwealth English genericised trade mark), sometimes known as a generic trade mark, generic descriptor or proprietary eponym, is a trademark or brand name which is often used as the colloquial description for a particular type of product or service as a result of widespread popular or cultural... Digital access and cross-connect system (DACS): In communications systems, a digital system in which (a) access is performed by T-1 hardware architecture in private and public networks with centralized switching and (b) cross-connection is performed by D3/D4 framing for switching digital-signal-0 (DS-0) channels... Western Electric (sometimes abbreviated WE and WECo) was a US electrical engineering company, the manufacturing arm of AT&T from 1881 to 1995 . ... In 1996, AT&T spun off its Systems and Technology units, along with the famous Bell Laboratories, to form a new company named Lucent Technologies (NYSE: LU). ...