Firstly you need to ask your current network for your PAC code (see below). Your PAC code is what enables you to move your mobile phone number from your existing network to your new network.
The PAC from your existing network is valid for 30 days. If you don't use it within 30 days you will need to get another one from your network.
If you tell us your PAC code on the phone we will transfer your number within 2 working days.
That's it! Once that is done your old number is set up on your new phone.