I recently switched to AT&T, and bought an iPhone 4S. I changed my mind, and decided that I wanted an iPhone 5 instead. When I went to a Best Buy Mobile store near me, I was told that there was a new policy "from Apple" stating that you could not exchange an iPhone 4 or 4S for an iPhone 5. The policy was new. I told them that I had just bought my phone a few days ago, and was in the return window, but they said they were not allowed to make the exchange. I was able to get my iPhone 5, but it required me making a call to AT&T Customer Support while in the store, putting them on speaker phone, and the AT&T rep suggesting the Best Buy employees doing something they did not want to do as a work around (i.e. having me port my phone number back to Sprint, return everything, and then start a new service line). Once this was suggested, they decided to no longer wait on their manager to get back to them via phone, and just went ahead and did the exchange for me. I would like to say that both Best Buy employees were very friendly and helpful regarding this situation, and did what they could to help me. AT&T said that no such Apple policy exists, and that it is probably a Best Buy policy. The employees did acknowledge that it could be a Best Buy policy, but said that it was just what they were told. I wanted to let everyone know about this just in case you are in my situation and took advantage of the cheap 4/4S price.