Can you unlock an AT&T samsung propel at an AT&T store?

I'm not too certain of your question. You have T-Mobile right now, are you going to transfer service to AT&T? You would have to, in order to get that deal. If this is the case, AT&T can and will give you the unlock code BUT only after you have been a customer for 90 days or so. Other than that, you can search your area for a store that unlocks phones or online.

You can get the unlock code here Unlocking4U- Unlock Your Phone It provides unlock code and instructions...By using this you can unlock your mobile successfully...

You need not go to any store to unlock your Samsung Propel. You can unlock it from your home itself through online. You can visit Unlock-Zone.com and get the accurate unlock code for your Samsung Propel at affordable cost with an easy unlocking guide. Good luck.