Every cellular-connected device has a unique serial number. These are most commonly seen on smartphones; however, unique identifiers are also present on cellular-enabled tablets, smartwatches, and more. These serial numbers are referred to as device identifiers, and they allow wireless carriers to identify the individual devices on their networks.
While all wireless carriers use device serial numbers similarly, there are different formats, such as MEID and IMEI. Quite often, people only think about device serial numbers during the initial activation with their carrier, but they are important. For example, if a device is reported as lost or stolen, the carrier can add the serial number to a universal blocklist, preventing the phone from being activated.
IMEI and MEID numbers are both used to uniquely identify your device, but the main difference between them is that MEID is used for CDMA phones and IMEI is used for GSM phones. Keep reading to learn more about what MEID and IMEI mean and how they differ.
MEID vs IMEI
What is an MEID?
MEID: Mobile Equipment IDentifier
MEID numbers are used on CDMA phones. The MEID format was initially created to replace the Electronic Serial Number (ESN) format, which ran out of unique numbers in late-2008. Because the MEID number is used to identify devices, they each need to be unique.
What is an IMEI?
IMEI: International Mobile Equipment Identity
IMEI numbers are used on GSM phones, and every phone (or other cellular-connected devices) will have a unique IMEI. Some phones, such as modern iPhones will also have two IMEI numbers — one that is attached to the physical SIM card slot, and another that is digital. The latter is often referred to as an eSIM.
What are the differences between MEID and IMEI?
The primary difference between MEID and IMEI is where they are used. MEID is used by CDMA (Code Division Multiple Access) carriers on CDMA networks, and the IMEI is used by GSM (Global System for Mobiles) carriers on GSM networks.
The formatting and length of these numbers also differ:
- Every MEID number consists of 14 hexadecimal digits, which are broken down as follows; two digits for the regional code, six digits for the manufacturer code, and six digits for the serial number. MEID numbers can also have an optional check digit, which would be in addition to the 14 hexadecimal digits, and not considered to be part of the serial number.
- Each IMEI number consists of 15 digits (14 digits along with 1 check digit). Unlike the check digit on the MEID, the check digit on the IMEI is considered to be part of the serial number.
Although these numbers are slightly different, they accomplish the same purpose: They both uniquely identify devices. This identity is key to using your phone, and you will not be able to activate a device if its MEID or IMEI has been blocked by a wireless carrier.
If you are planning to sell a newish phone, or buy a newish phone — you will want to make sure the device serial number is not on a carrier blocklist. If you are planning to get your newish phone from the Swappa marketplace, you can relax a bit because all listings have been reviewed by our moderation team, and that review includes a check of the serial number. However, if you plan to buy your phone from another (unknown) source, you can use our free IMEI checker by tapping on the green button below.