heres a data point for you guys. I just got my card in the mail today, activated it, found the link under my offers on the citibank website, followed the link to the att website where i activated the offer and bought a phone using the "replace my phone" option. Received an email from att immediately, stating:
Here's more information if you're replacing your phone.
This purchase will not affect any existing contract. Your upgrade eligibility will not change.
Here's more information if you're replacing your phone and are on the AT&T NextSM plan.
This purchase will not affect any existing contract. Your upgrade eligibility will not change. You will continue to be on your AT&T Next installment plan and will still be responsible for the remaining monthly charges.
Thank you for choosing us,
AT&T
pretty simple, and fast. ^