You can't port your number until your sim becomes fully active. Check to see if you have a phone number displayed in my giffgaff. Did you top up with £10.00 during the activation process?
If you're not sure, then did you go through the registration process as shown below:
1. Insert your giffgaff SIM into your handset.
2. Log in to your account
3. Click on this link when you've read the following: http://giffgaff.com/activate-sim
4. Enter your 6 digit Activation Code in CAPITALS. Ensure all letters and numbers are correctly entered as it is case sensitive (you'll find the Activation Code on the card that the sim was attached to).
5. Enter your top-up voucher number (a minimum of £10.00), or fill in your Bank details. You can also Activate with a £10.00 Goodybag. You can use a Giffgaff, or an O2 voucher.
(If you get a message saying "Voucher already used" then just try a little later as the system hasn't yet updated since you purchased your voucher).
You will now
have successfully registered your new giffgaff SIM card.
It will take from within 2 hrs., up to 24 hrs. to activate the sim.
When the sim is fully active, you will find your number, and your balance in My Giffgaff.
If you register after 10.00pm, the activation process will not commence until the following day.
Note: Don't discard your 6 digit code until you have received you phone number as you may need it if activation was unsuccessful.
I hope this helps you. rahoo.