Just have a quick question regarding returning or swapping a new iphone for those who may have done this with earlier models. I'm currently near the end of my Sprint contract for my launch day iphone 4s. I plan on getting one of the new iphone models coming out later this month but also looking at changing carriers at the same time. I'm looking to move to a prepaid T-mobile plan since it would be much cheaper than my current Sprint plan and T-mobile's LTE network is live in my area but no ETA on Sprint's roll-out. The only issue is I'm not sure how good T-mobile's coverage is at my place of work. To test, I bought a prepaid T-mobile sim and popped it into my unlocked original iphone. At least for voice/edge, the reception isn't as strong as Sprint's but good enough. I'm unable to test 3G/4G/LTE since I do not have a compatible device and all my coworkers are on ATT/Verizon/Sprint. So here's my question. If I purchase an unlocked iphone(5s/5c/whatever) and find the reception is too poor to stay with T-mobile, what is the return/exchnage policy at the Apple stores? I know there's the basic return policy, but is there any exchange policy with carrier models? If T-mobile's data service doesn't work well at my place of work, which is my primary concern, I'll most likely stick with Sprint. But that would require a Sprint iphone model. To note, I'll will most likely keep my Sprint account/4s active till I know that T-mobile service will work for me. Not including the chance of certain models/versions selling out during the release, how easy is it to take one carrier model back and exchange it for another carrier? Never ran into this since I went original iphone(ATT)->3Gs(ATT)->4s(Sprint). Would be interested in hearing from anybody who had a similar experience and what did they do. I'm assuming at this point i would have to just return the unlocked gsm version and then purhcase a Sprint model. If there's another way to do this, I'm all ears.