Thanks, JC. The coverage on that site only repeats the carriers' maps and that is part of the problem, since it is not accurate (for O2, anyway). I'm in the middle of the '20 working day' wait with OfCom.
The only way to be sure is to do your own survey with an Android phone and tools such as Cellmapper. If you have iPhone its not possible.
I can muster about 4Mb down with 4g on Three which I assume is fine for VOIP calls? When the copper landline and 2/3g go, how do the 'older' generation manage to make mobile calls if they have no 'smart' phone?
Most VoIP calls over an internet connection max out at 128kbps maximum for highest quality. 64kbps is still better than most traditional PSTN calls.
Legacy copper landline
voice service goes in 2025, but will be replaced by a box (needing power) that the phone handset plugs into and voice calls work. BT call this "Digital Voice". Its using VoIP technology, but not over the internet. The concern is for areas that have frequent power cuts, or are rural.
The box connects using ADSL or VDSL (FTTC) technology but doesn't need to go as far as the internet, and will be charged the same as the existing PSTN voice service.
Anyone that has voice & internet will work with their internet provider, and will plug the phone into back of the internet router. Some companies may chose to no longer sell voice services and will request you move to another provider.
I'm expecting things to get clearer after Sept 2023 when new PSTN lines are no longer installed. This is NOT the same as "copper" being removed/retired. The copper lines will last a lot longer.
23 years of broadband connectivity since 1999 trial - Live BQM