A standard PSTN voice connection continues to take the copper route. Just diverted through the FTTC one to pick up or drop the VDSL2 signal. This is exactly how voice and ADSLx works in the exchange. See also the FTTC page on my website.

The only times this isn't the case is when VOIP is used by the subscriber. This can be taken with or without a PSTN service, using different numbers, if supported by the ISP.

It is normally possible to port a PSTN number to VOIP, with or without retaining a PSTN connection. They still need different numbers.

Whether it is technically possible to run PSTN and VOIP with the same number I don't know. I doubt it, which is why I said above they have to be different. They normally are.

Just a bit of extra info.

The cab that Andrew thought could be Virgin Media or I suppose NTL (as it used to be around here) has no markings or plates at all. The manhole covers in front of it though have "CATV" marked on them. The other thing to note about this possible virgin cable cab is that unlike my BT PCP which has two securing points on the doors this has only one centerally mounted.

There were no other FTTC cabinets in the vicinity of my PCP either, so Andrew must be right.

From google/Wikipedia:

CATV (originally "community antenna television," now often "community access television") is more commonly known as "cable TV."

In reply to a post by ian72:

From google/Wikipedia:

CATV (originally "community antenna television," now often "community access television") is more commonly known as "cable TV."

Thanks Ian72, so that sort of indicates what has been suggested.

At least I can say with some confidence now that the FTTC cabinet which is a distance away from my PCP approx 30 - 40metres appears to be the correct pairing.

Yes, as has been confirmed, the CATV manhole chamber covers are VM or one of its predecessors that it bought.

What is the maximum number of PSTN lines through a PCP?

A lot. But it obviously depends on what size it is in the first place.

The PCP (one of the large ones) that serves my new place covers around 1100 addresses and that includes 80 houses on the new estate I'm moving to. The also two new developments, one starting this year and the other next year, which will be covered by the same cab and add another 240 addresses.