I was recently sent a replacement Samsung Galaxy S4 from T-mobile and the sticker behind the battery is not the same as the origianl phone that I had. The replacement phone's sticker does have an IMEI but it does not have a serial number on the sticker. I contacted Samsung and the rep told me that there is no way to track where the phone originated from and that the difference may just be whether the phone is locked or unlocked.
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How to tell if your T-mobile replacement phone is refurbished or new?