What is a CSU/DSU?
A T1 is made up of 24 digital channels. This requires a digital connection device (CSU/DSU {customer switching unit/digital switching unit}) to connect to four wires to carry the information. All T1lines require that a Channel Service Unit (CSU) be connected between your Data Terminal Equipment (DTE), i.e., a personal computer, and the T1 line. A CSU serves both as a surge protector (to protect your equipment from voltage anomalies such as lightning) and a monitor of the line itself. A CSU is used to connect Non Data Terminal Equipment to a T1 line. A CSU/DSU [Channel Service Unit / Data Service Unit] is a piece of equipment that connects a circuit to the customer’s equipment (such as a router). It performs line encoding and conditioning functions and often has a loopback function for testing. If your DTE doesn’t provide a “T1 Out” for a CSU, then a combined DSU/CSU will be required. Many of these devices include sophisticated performance monitoring and diagnostic capabilities. For ful
