welcome to Webune Support - today we are going to try to explain what a CSU/DSU Used For. in today's networks, its important to have backup bandwidth for your out of band systems. There are options which are provided by the CLECs to provide T1, T3 and OC dedicated circuits like Private Dedicated Lines.

so for example, lets say i leased an end to end T1 from AT&T. the A end is located in San Jose,CA and the other end is located in Bangalore,India. as the carrier drops my dedicated line to my site in San Jose, i need to connect that line to my Cisco 2600 router, in order for me to covert that T1 singal, i have to use a CSU/DSU which looks like exactly as the picture above.