I own a Cingular Wireless store and have found out from my vendors that there are a lot of Fake Motorola Razr cell phones in the market and are even being sold on ebay.  Almost 100% of the time these Razrs are unbranded or unmarked.  Unbranded means that they dont carry any service providers names on them, such as Cingular, T-Mobile.  Verizon also carries the Razr but Verizon Razrs are not affected because they dont work with GSM technology they are CDMA.  The real razrs have a laser etched Motorola M logo on the front and back of the phone.  The back one is on the battery door which is real easy to replace.  Keep a lookout for the front logo.  I have even seem some that the Motorola logo is an aluminum sticker.  Those are fake.  The real one is etched into the housing of the phone.

To be on the safe side purchase Branded razrs.  If you want a Black Razr for T-mobile, purchase an unlocked Cingular version and use it.  If you have noticed the Branded ones go for a little bit more on ebay, but it is better than getting a fake one.

The fake ones have a lot of problems and if you try to send it in to Motorola Warranty they will decline it because it is a fake one and they know by the serial and IMEI numbers on the back.