What is a CSU?
A CSU, or Channel Service Unit, is a compact piece of customer premises equipment that can be installed inline on a T-1 trunk immediately in front of a network interface device such as the Brooktrout TRNIC+I24T, or one of our PRI interface boards that doesn’t have an on-board CSU. The range of functions that a CSU may perform varies widely, but at a minimum it provides line conditioning, loopback and diagnostic capabilities. The signals present on a T-1 are susceptible to distortion as loop length increases and various types of interferences are encountered. The CSU reinforces these signals, keeps track of errors, and provides test modes to help resolve line problems. Another important function that many CSUs provide is called “keep alive” which, as the name implies, will keep the T-1 link up even if your network interface device goes down. This helps to avoid calls to your carrier to ask them to re-enable a T-1 that they shut down when they detected a problem with your equipment. CSUs
