I Want To Keep My Number
How do I keep my number if I am changing networks?
If you want to keep your number you'll need to get a PAC code (Porting Authorisation Code – its usually three letters and six numbers) from your existing provider. It’s free, it’s easy and lots of people do it. Just call them up and ask for your PAC.
You may also be able to get your PAC code online via web chats, email or even in the post. Ofcom says that your provider must give you your PAC code when you request it and that it has to be issued to you immediately over the phone or within two hours in a text message so you should have no problem.
Once you have it, you've now got 30 days to give the PAC code to your new network otherwise it'll expire. Your new network will take the PAC code and sort things out with your existing network, letting them know that there's a request to retain your mobile phone number. Your number could be transferred to your new network's SIM card as early as the next working day, but don't be surprised if it takes a little bit longer.