Hi @mparfitt1, thanks for your post although I'm sorry to hear of your concerns raised.
If you can get more information from your alarm provider, this might help you to make a decision - all UK landlines are going to be conecting to the fibre network by 2025, although we're just a little ahead of the curve so most alarm companies should be prepared for this now.
If you haven't received a letter yet confirming the date we're going to switch you over, I'd advise waiting for this and then contacting us once you've got this and we can take you from there with the relevant steps.
Many thanks
Tom_W