Contact Orange to request your "Port Authorisation Code" (PAC) at the same time you give your notice of leaving. The Orange customer support line for Pay Monthly customers is 07973 100 150 (or 150 from your mobile), and for Pay As You Go customers dial 07973 100 450 (or 450 from your mobile). Orange will then send out your PAC code by post within 2 working days.
Once you have received your Port Authorization Code from Orange, look for the best giffgaff offer that is suited to you. Many of the best mobile phone deals are available exclusively online, directly from the network providers listed here.
Finally, provide your PAC code to your new giffgaff mobile network operator who will then be able to port your existing phone number from Orange. They will tell you what day the transfer is due to take place (usually within 48 hours).
Important: Do NOT cancel your contract before switching, otherwise you might not be able to port over your number. Once you provide your new network provider with your PAC code, your old account will automatically be cancelled when the number is migrated over.
Note: Credit on a PAYG (Pay-As-You-Go) account cannot be transferred and any remaining credit will be lost after the switch over.
The first step is to join giffgaff.
Once you have done that, ensure you have the following information ready:
Make sure your giffgaff account and SIM have been activated. Then log in to your account and contact giffgaff to keep your old number. A Giff gaff customer support agent will then get back to you with your transfer date. Replies can be found in your giffgaff account message box.
Note: You may lose network service for a short period on the day of transfer. If this happens, turn your phone off and on occasionally, until you see the giffgaff signal on your mobile phone screen. This will indicate that the transfer is complete.
Visit giffgaff online for more information and their latest offers on mobile phones, contracts and PAYG deals.
Need some help? Ask over at the new Mobile Phone Forum