If you are thinking of leaving giffgaff then I hope it's for a reason not associated with a dissapointing experience, as good as giffgaff is we all know it doesn't fit everyone's requirements. So good luck with your new service provider and remember that even when you switch over and your sim is deactivated, your giffgaff account will always be available and up and running just like a Web email address. You can log in to your dashboard anytime you need to ask the fantastic guys on here any question regarding mobile or computer communications technology, no matter who you choose for your mobile services, and the guy's on here have no equal in that field.
TO TAKE YOUR NUMBER FROM GIFFGAFF.
Use this link to request to take your number to another network.https://giffgaff.com/profile/details#take-my-number
Please remember to log into your account and remove any payment methods like bank or credit card details.
Turn off any recurring goodybag settings and auto top ups that may be set up.
Once you have your PAC code you have 30 days to use it to port your number to your chosen network. And please remember you can always come back and activate a new sim card on your current giffgaff account anytime and once active you can port your number back.
Good luck and we all hope you keep in touch.