Buying a used phone, reporting a stolen one, or activating a new device on a network all come down to the same 15 digits: the IMEI. Most guides explain it in a sentence and stop. This one decodes every digit, shows you how to find your IMEI on any phone in seconds, explains how stolen-device blacklisting actually works, and covers what the number means for IoT and eSIM fleets. It serves two readers: the device owner who wants a quick, trustworthy answer, and the IoT or telecom team that manages thousands of these identifiers at once.

An IMEI (International Mobile Equipment Identity) is a unique 15-digit number that identifies a mobile device on a cellular network. It is tied to the physical hardware, not to the SIM card, so it stays the same when you change SIMs or reset the device. Networks read the IMEI to identify a device, verify that the make and model are approved, and block the device if it is reported lost or stolen. The standard is defined in 3GPP TS 23.003, the specification that governs identifiers across GSM, UMTS, LTE, and 5G networks.

What Is an IMEI Number? Meaning and Purpose

The IMEI is your device’s permanent identity. A manufacturer assigns it before the device leaves the factory, and it is globally unique, so no two devices legitimately share one. IMEI stands for International Mobile Equipment Identity, and that name explains the job: it identifies the equipment, separate from the subscriber. The subscriber identity, the IMSI, lives on the SIM. The device identity, the IMEI, lives in the hardware.

Every modern cellular network reads it. GSM, UMTS (3G), LTE (4G), and 5G all use the IMEI to recognize a device as approved equipment and to decide whether to admit it. A useful way to picture the IMEI meaning is a fingerprint for the hardware, or an equipment passport that a network checks at the gate. The phone carrier, an authorized manufacturer, or law enforcement can use it to identify a specific device, which is what makes it the backbone of stolen-device blocking.

One historical note for accuracy: older CDMA devices used a different identifier called an MEID instead of an IMEI. CDMA networks have been retired across the United States, so nearly every phone, tablet, and cellular IoT device sold today carries an IMEI. The IMEI is part of a wider family of identifiers, which we map in full in the Cellular Identifiers Hub.

IMEI Number Structure: What Each of the 15 Digits Means

An IMEI is 15 digits, and those digits are not random. They split into three blocks that answer three questions: which model, which unit, and is the number valid. Understanding the IMEI structure (sometimes searched as IMEI format) is what lets a tool decode a number into a real make and model.

Read as a format, the 15 digits look like AA BBBBBB CCCCCC D, where AA BBBBBB is the TAC, CCCCCC is the serial, and D is the check digit. For example, an IMEI example such as 49 015420 323751 8 (illustration only, not a real device) decodes to an 8-digit TAC of 49015420, a 6-digit serial of 323751, and a check digit of 8.

IMEISV: the 16-digit variant

You may also see a 16-digit number called the IMEISV (IMEI Software Version). It is the first 14 digits of the IMEI plus a 2-digit Software Version Number that tells the network which firmware the device is running. The number you get from *#06# is the standard 15-digit IMEI; the IMEISV is mainly used inside network signaling. So what is IMEI SV comes down to this: same device, plus a software-version tag.

The check digit and the Luhn algorithm

The 15th digit is a Luhn (mod 10) check digit calculated over the first 14. It is the same checksum that validates credit card numbers under ISO/IEC 7812. Its only job is to catch a mistyped or transposed number instantly, before a system tries to look it up. A Luhn check is why a good lookup tool can tell you a number is invalid without contacting any database.

Dual-SIM and eSIM phones: IMEI 1 and IMEI 2

A phone with two active radios carries two IMEIs, one per path, which is why people search for IMEI 1 and IMEI 2. Dual-SIM phones and many eSIM phones show both. Each line needs its own device identity to connect independently, so each gets its own 15-digit IMEI.

What Is a TAC (Type Allocation Code)?

The TAC (Type Allocation Code) is the first 8 digits of the IMEI, and it answers what is a TAC in an IMEI: it identifies the make and model. The GSMA allocates TACs to manufacturers, so a TAC is also a signal that a device passed type approval and regulatory checks. That is how a network can look at the front of an IMEI and decide whether the hardware is permitted to connect.

TAC databases map each code back to a specific device. Commercial lookup services track hundreds of thousands of device models (one well-known database lists more than 299,000), which is what turns a raw IMEI into “Apple iPhone 15 Pro” or a specific cellular module. For an IMEI TAC lookup, that mapping is the whole point.

Why the TAC matters beyond a single phone:

• Device-type analytics: operators and platforms read TACs to understand the device mix on a network.
• eSIM and network compatibility: the TAC confirms whether a model supports the bands or eSIM features a service requires.
• Fraud and fleet control: a TAC that does not match a device, or an unapproved TAC, is a red flag.

How to Find Your IMEI Number on Any Device

The fastest way to find your IMEI works on almost every phone, with no menus:

1. Open the phone dialer, as if making a call.
2. Type *#06#.
3. Your IMEI appears on screen instantly. On a dual-SIM or eSIM phone you will see two numbers, one per line.

If you prefer the settings menu, or the device is off, use the table below.

This covers the common device questions, from IMEI on iPhone and what is IMEI on iPhone to how to get IMEI on Android and finding it on a Pixel, Samsung, or Motorola. Once you have it, write it down and store it somewhere safe. You will need the IMEI to report a device if it is ever lost or stolen.

What Is an IMEI Number Used For?

The IMEI does five jobs, and most people meet it through one of them: checking a used phone, reporting a stolen one, or activating a device.

1. Device identification: networks read the IMEI to recognize the equipment, separate from the subscriber on the SIM.
2. Theft prevention: carriers and shared registries blacklist a reported IMEI so the device cannot get cellular service. More on this in the next section.
3. Warranty and insurance: manufacturers and insurers verify a device by its IMEI for claims and support tickets.
4. Carrier eligibility and unlock: a carrier checks the IMEI to confirm a device is compatible, unlocked, and clear to activate. eSIM activation also references the IMEI.
5.  Analytics and compliance: operators and connectivity platforms use the TAC inside the IMEI to map the device mix on a network and confirm approved hardware.

So what is the IMEI number used for in one line: it is how the mobile ecosystem identifies, approves, and protects a device throughout its life.

IMEI Security: Cloning, Blacklisting, and Blocking Explained

This is the part most IMEI guides skip, and it is the part that protects your money. If you are buying a used phone, this section is the reason to run a check first.

How IMEI blacklisting works (and why to check before you buy)

Blacklisting runs on three layers, and knowing them explains why a stolen phone gets blocked everywhere:

1. Operator EIR. Each carrier runs an Equipment Identity Register that marks an IMEI as allowed, monitored, or barred.
2. National CEIR. Many countries run a Central Equipment Identity Register that shares barred IMEIs across all domestic operators. India’s CEIR is the best-known example.
3. GSMA global registry. The GSMA Device Registry shares barred IMEIs across borders, so a phone stolen in one country cannot simply be reactivated in another.

When you report a device lost or stolen to your carrier or the police, your carrier adds the IMEI to these lists. The practical result: a blacklisted phone can still join Wi-Fi, but it cannot get cellular service on any participating network. That is why you should always run an IMEI blacklist check before paying for a used phone. Skip it, and is my phone blacklisted becomes a question you ask after you have already lost the money on a device you can never activate.

If your own device goes missing, act fast:

1. Call your carrier and report the device lost or stolen so they bar the IMEI.
2. File a police report and include the IMEI.
3. Use your device platform’s remote lock and erase to protect your data.

Can an IMEI be changed? And what is IMEI cloning?

Two related questions, can an IMEI be changed and IMEI cloning, have the same root answer: the IMEI is meant to be tamper-resistant in hardware, and altering it to disguise a device is illegal in most jurisdictions. The lawful exception is a genuine repair that replaces the logic board, which can legitimately change the IMEI.

IMEI cloning copies a valid IMEI onto another device to dodge a blacklist or impersonate approved hardware. It is illegal, and it is the reason two devices should never share an IMEI. Warning signs include a device whose IMEI does not match the number on its box, or a carrier flagging a duplicate. The GSMA is also extending blocking to eSIM, work that advanced through 2025, to make stolen devices even harder to revive.

US carrier IMEI rules

Verizon, AT&T, and T-Mobile each check the IMEI before they let a device on the network. The check confirms three things: the model is compatible, the IMEI is not barred, and the device is eligible to activate or unlock. A barred or incompatible IMEI is simply refused, which is one more reason the number matters when you switch carriers or buy secondhand.

IMEI vs IMSI vs ICCID vs Serial Number

These four are easy to confuse because they all sit on the same device. The difference is simple once you see what each one identifies.

• IMEI vs IMSI: the IMEI is the device; the IMSI is the subscriber on the SIM.
• IMEI vs ICCID: the IMEI is the device; the ICCID is the SIM card or eSIM profile.
• IMEI vs serial number: the serial number is the manufacturer’s own unit ID, while the IMEI is a standardized identity that networks read. A phone has both, and they are not the same.

For the SIM-side identifiers, see the ICCID guide and the multi-IMSI versus eUICC guide. 

IMEI in IoT and eSIM Devices

The IMEI is not just a phone thing. Every cellular IoT device ships with one, tied to its modem or module, from asset trackers and EV chargers to routers, medical monitors, and connected vending units. The TAC identifies the module model, which is how a connectivity platform confirms the device is certified for a given network before it is allowed to connect.For a fleet, the IMEI is the stable anchor for the entire device lifecycle: provisioning, status and diagnostics, usage attribution, and retirement. That stability is what makes it useful, because the SIM-side identifiers can move. An eSIM device can hold several profiles, each with its own ICCID and IMSI, and switch between them over the air. Through all of that, the IMEI stays fixed for the life of the device.

The practical problem for any team running devices at scale is tracking the IMEI, EID, ICCID, and IMSI for thousands of units across multiple carriers at once. That is the job Spenza was built for: a multi-carrier eSIM and connectivity platform that manages every device identifier from one place. If you are deploying connected devices or an IoT fleet, see how Spenza handles identifiers at scale.

What an IMEI Does NOT Reveal: The Privacy Question

It is worth being clear about what the IMEI is not, because the fear that “my IMEI tracks me” is common and mostly misplaced. An IMEI identifies the device, not you. It does not contain your name, your location, your contacts, or your browsing history. By itself, it cannot follow your movements.

Locating a device by IMEI requires access that only your carrier and law enforcement have, normally under a lawful request. That is the same channel that lets a stolen device be traced and blocked. So the honest summary is this: treat your IMEI like a serial number. Do not post it publicly, and only share it with your carrier, your insurer, or a buyer during a verified sale.

The Bottom Line

Your IMEI is your device’s unique and permanent identifier. Whether you’re buying a used phone, managing a fleet of connected devices, or trying to recover a lost device, knowing your IMEI matters. Always verify the IMEI before purchasing a secondhand device, and report it immediately if your device is lost or stolen.

Use the IMEI lookup tool above to validate any IMEI and decode its TAC directly in your browser.

Managing Devices at Scale?

Keeping track of a single IMEI is easy. Managing thousands of SIMs / eSIMs across multiple carriers is a different challenge.

Spenza simplifies cellular device management with a multi-carrier eSIM and MVNE platform that brings all your cellular identifiers into one centralized dashboard. Provision, monitor, and retire devices without switching between carrier portals or managing complex carrier relationships.

Talk to the Spenza team to see how streamlined cellular connectivity management can be.

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