Hello,
whar are the diferences ,if any, between the CSU and the NIU ?
Thanx a lot for your help

The NIU is the provider's demarc point of the circuit. The point they will test to when any troubles occur.

The CSU (if one is present) is a connection point between the NIU and the CPE (customer premise equipment, EI:router or PBX). The CSU can also be looped as a test point by the carrier.

Although most circuits will operate normally without a CSU it does provide a protection point between the demarc and the equipment.

Most CSU's are powered by local AC power so remember to include them in your battery back up/ups plans. the circuit will go down if the CSU loses power.

D