Us you can. See here for process
Activate. a sim details. Log in here to start.
Http://giffgaff.com/activateEnter the six character code and touch ". "continue "
Look at the address bar to see either MGM(member gets member) or freedom. MGM will mean the sim had £5 free on it. Freesim means the sim is standard and no bonus.
On this page you can pay by card or voucher(vouchers can be bought from shops displaying Pay Point etc banners). Follow steps to pay by card (the card has to be UK registered with a UK billing address ).
If you use a voucher look carefully for where it says " if you have top up voucher ". Touch.
The next page is personal details. Enter or change as necessary. Then touch "continue ".
This page gives a prompt for the 16 digit code on the voucher. Enter the 16 digits with no gaps then touch "redeem ".
All done.
The activation now starts.
Full activation can take up to 24 hrs. but normally it's only 30 minutes.
Sim actived? Check online here to see your new giffgaff number and your balance, when you see them your sim is activated.
Http://j.mp/my_giff