[MovedGoalPosts]

What exhange you are connected to depends on the layout of the wiring buried in the streets. Phone and cable wires will eminate from an exchange in an increasing maze of branches and twigs from a few trunks. There are then separate cables that link between each exchange.

Ultimately which exchange your property connects to will have been determined in years gone by by the network planners who had regard to echange capacities, local constraints for ducting routes (perhaps there were rivers, rail lins, main roads), local authority and postal boundaries, and even for cable companies the geographical franchise areas they were awarded.