The restriction code is the unlocking code to allow you unlock the phone from being useable just on 3 network. It means that you'll be able to use the phone on any network you choose. You can get the code directly from 3, or from a shop or market stall that does phone unlocking. After it's unlocked, you'll need to get the settings from your new company, such as call settings, text, internet, etc. Hope this helps.