If you are changing broadband providers you can always choose to keep your phone number.
It’s not a difficult thing for ISPs to do, normally, because nearly all broadband providers in the UK use the nationwide Openreach network.
So even if you’re changing from Sky to TalkTalk, or BT to Plusnet, you should be able to keep your phone number.
Just ask your new broadband provider and they’ll help you through the process.
The only different one is Virgin Media.
Virgin Media build their own cable networks and don’t use Openreach like everyone else, so if you are switching to Virgin, your phone number will need to be transferred to the new network.
Simply tell Virgin that you want to keep your number when you sign up for a phone or broadband deal and they’ll take care of the rest.