To run an IMEI carrier check for free, run the IMEI in a free online service such as IMEIData.net or IMEI.info. Additionally, iPhoneIMEI.info offers a service for specifically checking iPhone IMEIs.
The international mobile equipment identity code, or IMEI, uniquely identifies every mobile phone. To get your device's IMEI, simply dial *#06# on the dial pad. Alternatively, check whether it's printed on the phone's battery compartment. IMEIs of mobile phones that are connected to either a GSM or a UMTS network are registered in a special database called the equipment identity register, which contains information on all valid mobile phone equipment.
Information that can be derived about a phone based on its IMEI number includes the brand and model of the phone, the manufacturer, the SIM card size, the phone's band and its operating system. An IMEI check also reveals whether a device has been blacklisted, which happens when the owner reports it lost or stolen.
IMEI codes consist of four main parts. The first and second set of numbers denote the allocation body and the type allocation code, or TAC, respectively. The third set is the serial number of the device, and the fourth set is the Luhn checksum.