BT line and Talktalk call provider

Heinz

You missed my point. BT Retail has not applied a change to its service to its customers, the calls provider chosen by some customers has.

BT Retail knows which of its customers uses another calls provider for their calls and it knows which calls provider that is. However, because it is a commercial-in-confidence issue between BT Wholesale (a separate company to BT Retail) and the calls provider in question, BT Retail does not know how that calls provider is providing that service and, hence, BT Retail cannot 'warn' its customers of the incompatibility other than in the generic terms detailed in that link in post #4.