WHAT IS A PAC?
'PAC' stands for Port Authorization Code, but it's usually referred to as a PAC code or PAC number. Having this code allows you to take your mobile number from one network to another, so that you can continue to use your existing mobile number with a new contract or service with a different mobile network. A PAC number itself is normally 3 letters and 6 numbers long, and is unique to your mobile number.
How to get Pack Code
Your PAC can only be provided to you by the mobile network you wish to leave. To obtain the PAC you will need to contact your old mobile network and they'll provide this code to you. In almost all cases, you simply have to give the network customer services a call and ask for the PAC. It is valid for 30 days, so be sure to get it to your new network quickly. To make it easier for you, here are the contact details for the most popular UK networks: