Digital access carrier system

For almost as long as telephones have been a common feature in homes and offices, telecommunication companies have regularly been faced with a situation where demand in a particular street or area exceeds the number of physical copper pairs available from the pole to the exchange.

The more modern ISDN technology based digital systems that perform this task are known in Britain by the generic name 'DACS'.

DACS works by digitising the analogue signal and sending the combined digital information for both lines over the same copper pair between the exchange and the pole.

DSL broadband internet connections cannot work on a DACS line as they rely on a copper pair running all the way to the telephone exchange.

There are 3 basic types of Telspec RU: internal (skirting board mountable), external (pole mount) and underground (for manhole).

It then communicates the results back to the EU digitally, where mimics are presented to the normal exchange testing equipment.

WB900 – an analogue radio frequency based system that did not support even low speed data communications.