“Reprogramming” a mobile phone involves hacking its software in order to change its identity. A mobile phone’s international mobile equipment identity (equivalent to a car’s vehicle identification number) is altered for the purpose of illegal resale. Based on a two-pronged study, the authors conservatively estimate that 5 percent of mobile handsets are illegally reprogrammed. Unique identification should be an aim for manufacturers of all valuable products. Unique identification makes it possible to track, detect, and deactivate stolen items. In two surveys of mobile phones, the focus was on checking the identity of two samples of phone handsets. Determining whether a mobile phone has been reprogrammed is relatively easy. A mobile phone’s international mobile equipment identity (IMEI) is a 15-digit number unique to each mobile phone. The number is located in two places on every handset. The first location is in the phone’s software. It is displayed on the screen when *#06# is typed into the keypad. The second location is a “hard” copy etched onto a number plate. This plate is normally located under the battery inside the back of the phone. For any given handset, the numbers at the two locations should match. If they do not match, then the identity of the phone has been changed, probably by modification of the software. If the IMEI number plate is missing, then this is an indicator that the phone may have been stolen, because the number plates are difficult to remove, suggesting that such removal is intended to hide the phone’s original identity. 1 table and 11 references