Thanks for posting and welcome to the community.
Changing to the phone service via cable is a government objective and this has to be completed by 2025, we are choosing to take the change over now to ensure all of our customers have been migrated prior to the current telephone exchange being closed down in 2025.
See the following links below;
Need a helpful hand to show you how to make a payment? Check out our guide - How to pay my Virgin Media bill