Two years ago for Christmas, DH, gifted me with an iPhone from AT&T. It was a complete surprise! He activated it as a new phone with a brand new number before leaving the store. After opening it, he informed me we could keep it with the new number or go into the AT&T store and have the 'port' over my number from another cellular provider. It took all of 15 minutes (most of that waiting for my turn) to change the number.
Then we took it to the other provider's store and had them use their magic to get all my contacts to convert over.
Soooo, I would think (but you'll have to do some research with
Target and maybe with Apple) that maybe you can activate a new phone, under the new contract, and then have everything changed
over after he opens the gift on Christmas morning. Is current contract fulfilled?
Or, instead of all the headache...you could upgrade through the upgrade app. That's how I ordered my replacement for this year's present. It isn't
activated yet but I have the phone. Now, it was $199, but AT&T discounted my $30 monthly fee for
smartphones by $6.40/month which will only take 4 months to recoup the difference in phones.
HTH