The technology that we currently use to make landline phone calls is being upgraded over the next few years. Here's what this means for you as a customer.
"Changes to landline telephones | Age UK" https://www.ageuk.org.uk/information-advice/money-legal/consumer-issues/changes-to-landline-telephones/
"Moving landline phones to digital technology: what you need to know - Ofcom" https://www.ofcom.org.uk/phones-telecoms-and-internet/advice-for-consumers/future-of-landline-calls
The changeover needs to happen by December 2025, as this is when the old technology will stop working. Phone providers have already started work on switching over the network, but you don’t need to do anything until they get in touch with you.
Make sure this is by your official provider not someone who contacts you out of the blue, so be wary of scammers.