If you have an existing active PSTN-only line then the recently announced Openreach 'SOTAP for analogue' product once it reaches retail sellers (I suspect only BT will be interested given the likely low numbers) will do.

There is absolutely no change at the customers premises - the connection to existing exchange equipment, due to be shut down at the end of 2025, is moved to what is effectively a multi-port ATA and the conversion to VoIP done there rather than at the customer.

It's currently unclear to me whether "SOTAP" refers to the low-speed (1Mbps) digital service for voice-only lines, or an analogue service supplied by media gateways in the exchange.

If you have a POTS line from BT and they migrate you onto the latter, then as you say, you should be good at least until local exchange closure.

Do you have any other buildings nearby? Your long term solution may be to run a cable to another building and plug into an ATA. Or just carry a mobile phone.

In reply to a post by candlerb:

It's currently unclear to me whether "SOTAP" refers to the low-speed (1Mbps) digital service for voice-only lines, or an analogue service supplied by media gateways in the exchange.

The original SOTAP product which was proposed some time ago, in trials this year, and as of today a launched product is naked ADSL with no PSTN service, i.e. the equivalent of SOGEA being naked VDSL with no PSTN, so you have broadband service and optionally VoIP over the broadband.

The recent 'SOTAP for Analogue' product only recently came to light https://www.ispreview.co.uk/index.php/2023/11/openre... but it hasn't been launched yet.