1) Check you’re eligible to switch from giffgaff
Assuming you’re out of contract, it won’t cost you anything to leave giffgaff. If you’re not sure whether you’re still under contract or want to find out your contract end date, you’ve got a few options.
The first is to log in to your account at giffgaff’s site.
The second is to log in to the giffgaff app on your phone.
As you’ll almost certainly know, giffgaff doesn’t operate a telephone customer support service. So you won’t be able to get in touch over the phone.
2) Contact giffgaff to cancel your contract and get a PAC Code
With your phone wending its way to you, you’ll now need to contact giffgaff to tell them you’d like to leave and get a PAC Code. A PAC is a short, alphanumeric code, which is critical for transferring your number to the network you’re joining.
You can get your PAC code from giffgaff by logging into your account online and requesting one.
Or you can get one by texting 43431 from your giffgaff phone.
All networks are obliged to supply your PAC within two hours of your request. Once you’ve got it, you may want to make a note of it. Just in case.
PAC Codes are valid for 30 days only. If you haven’t used yours within this timeframe, you’ll need to submit a request to giffgaff for a new one.
3) Find and buy a new deal from O2
Your next task is to choose and sign up for a new deal contract from O2. Once you’ve passed O2's credit checks, you’ll receive your phone or SIM card in the post.
4) Contact O2 to give them your PAC code
Now you’ll just to ring O2 to give them your PAC. You can get in touch with O2's customer support team on 034 4809 0202 from a landline (standard network rates apply).
5) Insert your new SIM card from O2
If you got a new phone, use your pin-key to unlock the handset's SIM tray. Then insert your O2 SIM.
If you went for a SIM-only deal, you can just put the O2 SIM in your existing phone.
While your number is being transferred, you'll be supplied with a temporary number to use. So you can still make and take calls and do whatever you'd normally do on your phone.
6) Wait for your number to be transferred from O2
The transfer should be complete the next working day. But this varies depending on the network you're joining.
The transfer could also take a little bit longer if a weekend or Bank Holiday gets in the way.