Perform an International Mobile Station Equipment Identity number search on numerous websites, such as Swappa.com or IMEI.info, or on carrier-specific websites such as T-Mobile.com. Swappa also allows users to perform electronic serial number and Mobile Equipment Identifier number searches. These searches are typically used to determine whether or not a device has been blocked or blacklisted from use by the carrier from whom the device was purchased or by whom it was financed.
Due to many instances of private vendors selling mobile phones that they knew were blacklisted, any potential buyer should check the IMEI number of the phone that he is planning to purchase to verify that he can use the device. Most carriers offer IMEI checks on the company website so that consumers can verify whether or not their new devices can work with their phone service provider.
Each mobile phone has its own unique IMEI number, which acts like the phone's fingerprint. When a customer does not finish paying for a phone that was being financed, that phone's IMEI number is put onto a blacklist that is circulated among mobile phone carriers. This list allows phone carriers to share a common database of unserviceable devices with the intention of reducing the number of stolen phones that are resold to other consumers.