Hi @meself1 Do not cancel TalkTalk as this will result in her losing her telephone number. Order BT (or other provider) first to get the best result. You can always cancel TalkTalk if needed afterwards.
Bear in mind the move to BT will involve her landline being moved to Digital Voice. A move to another supplier may involve the loss of landline completely.
In what way is Talk Talk a problem, it may be better to just stick with them.
Can i suggest you do wait then, there are processes that are best to follow (as already mentioned) & once full info is available it can be 100% answered but if iit involves porting of a number 100% don't cancel her current connection
TT is overly expensive what she gets, plus there's been a constant echo on her landline which they've been unable to fix for over a year. Even a visit from one of their engineers failed to solve that problem.
The echo on the landline is because TalkTalk use MPF or LLU (their own equipment in the local exchange).
If you place an order with a new provider and opt to keep the telephone number, it should trigger a ‘sorry you’re leaving’ notification from TalkTalk.
There is a copper to fibre migration journey built these days. My friend ordered full fibre from Sky and that ordered triggered the cease order on their BT service (copper broadband with digital voice).
So go ahead and place the order.