When your telephone line arrives at the local exchange, the ADSL and voice components of the signal are split apart in the same way as your splitter works at home or in the office. The voice wiring is connected to BT's PSTN network (which we do not cover in this guide) and the ADSL wiring is connected to a device known as a DSLAM.
The picture (above, right) shows a series of Fujitsu patch panels used to split wiring pairs into their respective POTS and ADSL components. All telephone lines are connected to panels on the right side and ADSL lines are fed into patch panels on the left side ready to connect to the DSLAM. Click on the picture for a larger image.
The picture (left) (courtesy of easynet) shows ADSL copper pairs running down the left side into a patch panel used by engineers to easily connect or disconnect customers.
Depending upon the size of the local exchange, batches of 192, 256 or more copper pairs are connected to patch panels at the same time. An exchange serving a large or broadband hungry population may connect dozens of new customers per week so it's imperative that spare capacity is readily available.
Each white wire running up the right side is connected to a line card in theDSLAM serving multiple customers.