MEID vs. ESN vs. IMEI: The Difference Between Each and Why You Should Care

Just like any other electronic device, your phone has a unique serial number that identifies it from all the other similar phones that are mass produced. So if it gets lost or stolen, there is something to help you indicate this phone does belong to you.

You can use this number to track or detect a lost or stolen cell phone.

Perhaps however, you just want to transfer your phone to a different carrier, and unlock your phone. These unique identifiers are necessary for phone companies to relinquish their hold on your phone network, directly from your phone, in order to be able to use it on another carrier’s network.

ELECTRONIC SERIAL NUMBER (ESN)

An Electronic Serial Number, or more commonly referred to as your ESN, is what uniquely identifies a phone that works on a CDMA Network. The ESN were created by the Federal Communications Comission (FCC) to identify mobile devices in the United States, in the early 1980’s. The Telecommunications Industry Association took over the responsibility in 1997, and is still maintained by them.

They are only assigned to phones on a network that uses CDMA technology, like Sprint or Verizon. It allows the phone to be validated and connect directly to the cell tower. The ESN is embedded or inscribed on the microchip inside a smartphone by the manufacturer.

When a call is placed, the ESN is automatically transmitted to the wireless frequencies between your smartphone, and the network itself to the base station, to ensure the validity of the call.  The ESN cannot easily be altered in the field.

The ESN differs from the mobile identification number (MEID), which is the wireless carrier’s identifier for a phone in the network. Network Carriers will block this particular number to the phone, and “blacklist” that particular phone from being able to connect to any network provider in the US. This is very important to know if you are buying a carrier unlocked phone, and use it for your carrier.

It is composited of 11 unique numbers & letters. In 2005, ESN’s have begun to run out, the Mobile Equipment Identifier (MEID) began to replace the ESN,  and the first MEID was implemented by Verizon in 2006. They are the same length as the International Mobile Equipment Identifier (IMEI) in SIM card activated phones.

Mobile Equipment Identifier (MEID)

Because ESNs have begun to run out, and are no longer being used, a new numbering system was created by a company called 3GPP2. This organization was essentially the collaboration of telecommunication carriers that were embarking on the 3G network at the time, and was first used by Verizon Wireless.

While MEIDs were created to replace ESNs, it is often needed for compatibility purposes, and devices with an MEID will often use a pseudo ESN, called a pESN, which is a manufacturer code to ensure the phone works properly on the network. As of August 2016, the Telecommunications Industry Association (TIA) is the primary organization which assigns the unique MEID and the ESN counterparts or pESN to the phone.

International Mobile Equipment Identity (IMEI)

For nearly all phones outside of the US, and for any phone that uses a SIM card to operate on a carriers network, they assign an IMEI number. Global System for Mobile Communication (or GSM) use these unique identifiers to identify valid devices, and stop stolen phones from being utilized on a network. It also only has 14 digit numbers, compared to 15 digits for the MEID.

There are several countries that have laws and regulations, which utilize the IMEI to reduce the effects of smart phone thefts. For example, Senator Chuck Schumer proposed a bill in the US that would have made the changing of an IMEI illegal. Unfortunately the bill did not pass. However, under the Mobile Telephones (Re-Programming) Act in the UK, changing the IMEI of a phone, or possessing equipment that can change it, is considered a legal offence under some circumstances.

Of course, IMEI blocking is not the only way to fight phone theft. Especially if you believe there is the possibility of recovering your stolen phone, and you don’t want a nonworking phone. There are also Antitheft apps & IMEI tracker apps which allow you to track stolen phones, using the IMEI number. Mobile networks are always encouraged and offer the ability to provide immediate suspension of service, and replacement of SIM cards in case of loss or theft.

Thieves of course don’t take into consideration that most mobile networks or local operators maintain an Equipment Identity Register (EIR), and adds the IMEI to it. The IMEI can also be added to shared registries such as the Central Equipment Identity Register (CEIR), and will block the device from being used on any other operators using the CEIR. It basically makes it pointless to steal the phone, except for parts, which is more time an effort than any thief really wants.

In order to make these blocklists actually work, the IMEI number is supposed to be hard to change. Of course, an IMEI can be changed with apps, or other special tools, and a spoof IMEI can be created to get phones working on a different network.

Several countries began this IMEI blocking on GSM networks. The first nation to do this was Australia in 2003, under the Electronic Information Exchange (EIE) Administration Node, which holds all the blocked IMEI numbers for Australian customers. In New Zealand, there is the NZ Telecommunications Forum Inc which provides a blocked IMEI lookup service, and cannot be connected to the three mobile network operators in that country. Latvia has a program called the SIA “Diatorikas instituts DIVI” which provides a blocklist for all major networks in the country.

Of course, in other countries, blocklisting isn’t exactly the norm. It took another decade before networks in the US committed to blocklisting services in 2012.

If you are buying a used, network unlocked phone, be sure to check and see if the IMEI, MEID, or ESN is still valid and not on a blocked list. If you’re a buyer, and planning to buy a phone that is used, or through someone other than a legitimate mobile store, you can call the carrier up or visit one of the corporate offices to see if you can work something out when a phone is blacklisted.

The original carrier can perform an IMEI check to find out the reason the phone was blacklisted in the first place, and you may be able to work something out if it was merely that a person stopped paying on the phone. If it was reported stolen, they require you to surrender your phone to the carrier, and you’re out however much you paid for the phone.

Although all of these numbers are different in their own way, they accomplish the same goal: to uniquely identify a device, and in some cases, create some safety in thefts. It is key to using a phone on any given network.

If this identified number is put on a block list, there is no way around unlocking it. At least within your country. These identifiers can be found either etched on the back of the phone, behind the battery (for those phones with removable batteries), in your settings, or if you punch in *#06# in your phone dial pad.