What Is an IMEI Number? Complete Beginner’s Guide for 2026

Your phone has a name. Not its model name — a number burned into its hardware that identifies it uniquely on every network in the world. That number is the IMEI. If your phone is ever stolen, lost, or misused, the IMEI is the single piece of information that can get it blocked, traced, or recovered. This guide explains exactly what it is, how it works, and why you should care.

Table of Contents

1. What Does IMEI Stand For?
2. How Long Is an IMEI Number?
3. What Is an IMEI Number Used For?
4. Where Can You Find Your IMEI?
5. How Does IMEI Tracking Work?
6. Can You Check If Your IMEI Is Blacklisted?
7. How to Block a Phone Using Its IMEI
8. Is IMEI Tracking Legal?
9. IMEI vs Serial Number vs MEID
10. Frequently Asked Questions

What Does IMEI Stand For?

IMEI stands for International Mobile Equipment Identity. It is a unique 15-digit number assigned to every mobile device — smartphone, tablet, or cellular-connected smartwatch — that uses a GSM, LTE, or 5G network. No two devices in the world share the same IMEI. It was introduced in the early 1990s as the global standard for identifying mobile hardware, and it is governed by the GSMA (Global System for Mobile Communications Association).

Think of the IMEI as your phone’s passport number. Just as a passport number ties a document to a specific person, the IMEI ties a network connection to a specific physical device. When your phone connects to a mobile tower, the carrier reads its IMEI automatically — before any call is made or data is sent.

How Long Is an IMEI Number?

A standard IMEI number is exactly 15 digits long. It is broken into four segments:

Segment	Digits	What It Means
TAC (Type Allocation Code)	First 8	Identifies the device manufacturer and model
Serial Number	Next 6	Unique per device within that model
Check Digit	Last 1	Validates the IMEI using the Luhn algorithm

Dual-SIM phones have two IMEIs — one for each SIM slot — referred to as IMEI1 and IMEI2. Both are registered to the same physical device. Some older CDMA devices used a 14-digit MEID instead, but modern 4G and 5G phones universally use the 15-digit IMEI format.

What Is an IMEI Number Used For?

The IMEI serves three critical purposes in the global mobile ecosystem:

1. Device Authentication on Networks

Every time your phone connects to a carrier network, the network checks your IMEI against its Equipment Identity Register (EIR). The EIR has three lists: a whitelist of approved devices, a greylist of devices under monitoring, and a blacklist of blocked devices. If your IMEI is on the blacklist — because it was reported stolen or is unregistered — the network can deny service.

2. Theft Reporting and Device Blocking

When a phone is stolen, the owner can report it to their carrier, who then adds the IMEI to the national blacklist. From that moment, the phone cannot connect to any network that participates in blacklist sharing — even if the thief inserts a new SIM card. In countries with a national CEIR (Central Equipment Identity Register), like India, the block is enforced across all domestic carriers simultaneously. Learn how IMEI blacklisting works in detail.

3. Pre-Purchase Verification

Before buying a second-hand phone, you can check its IMEI against official databases to confirm it is not stolen, blacklisted, or carrier-locked. This is one of the most important steps anyone should take when purchasing a used device. A clean IMEI check takes under 60 seconds and can save you from buying a phone that will not work on any network. See our full guide to checking IMEI before buying a used phone.

Where Can You Find Your IMEI?

There are five ways to find your IMEI number, and all of them are free:

1. Dial *#06# — Works on virtually every phone. The IMEI appears on screen instantly.
2. Settings app — Go to Settings > About Phone > IMEI Information (Android) or Settings > General > About > IMEI (iPhone).
3. SIM tray — On many iPhones, the IMEI is laser-etched on the SIM tray itself.
4. Phone box — The original retail box has a sticker with the IMEI barcode.
5. Apple ID / Google Account — Both platforms store the IMEI of registered devices. Useful if your phone is lost.

Write your IMEI down and store it somewhere safe — a notes app, email draft, or even a piece of paper in a drawer. If your phone is stolen, you will need it to file a police report and request a carrier block. Full guide: How to find your IMEI on any device.

How Does IMEI Tracking Work?

IMEI tracking is not the same as GPS tracking. It works at the network infrastructure level, not through a location app. Here is how it works:

When a phone connects to a mobile tower, it sends its IMEI to the carrier’s network. The carrier logs which cell towers the device connected to, and at what times. This creates a trail of approximate location data. Law enforcement with a valid court order can request this data from the carrier to trace the last known location of a device.

Private individuals cannot access this data. Only carriers and authorized law enforcement agencies have legal access to real-time IMEI location data. Apps that claim to offer “IMEI tracking” without carrier access are misleading at best. Read the full technical explanation of how IMEI tracking works.

Can You Check If Your IMEI Is Blacklisted?

Yes. Most countries offer an official online portal where you can check your IMEI status in under a minute. Here are the most commonly used ones:

Country	Official Check Portal
USA	CTIA IMEI checker or carrier portal
UK	checkmend.com (GSMA-linked)
India	CEIR portal (ceir.gov.in)
Pakistan	DIRBS portal (dirbs.pta.gov.pk)
Australia	AMTA IMEI checker
Canada	Carrier portals (Bell, Rogers, Telus)

A clean IMEI check shows the device as “whitelisted” or “not blacklisted.” A flagged result means the device was reported stolen, is carrier-locked, or has a financial hold on it. Always check before purchasing any used phone.

How to Block a Phone Using Its IMEI

If your phone is stolen, blocking it by IMEI prevents the thief from using it on any participating network — even with a new SIM card. The process varies slightly by country, but the general steps are:

1. File a police report and get a case number.
2. Contact your mobile carrier and provide your IMEI and the police report number.
3. Your carrier submits the IMEI to the national blacklist (and to GSMA’s international database where applicable).
4. The block propagates within 24–72 hours across participating networks.

In India, you can also submit directly to the government’s CEIR portal without going through your carrier first. In the UK, you can use the National Mobile Phone Register. Full step-by-step guide: How to block a stolen phone using IMEI.

Is IMEI Tracking Legal?

Yes — with important caveats. Carriers are legally permitted to track and log IMEI data as part of normal network operations. Law enforcement can access this data with a valid warrant. Manufacturers use IMEI data for warranty and device registration purposes.

What is not legal is using IMEI data to track another person’s device without their consent or without proper legal authorization. In most countries, this would constitute illegal surveillance. The GSMA’s guidelines and national telecom regulations in the USA, UK, EU, India, and Australia all impose strict rules on who can access IMEI location data and under what conditions.

IMEI vs Serial Number vs MEID

Identifier	Length	Used By	Purpose
IMEI	15 digits	GSM/LTE/5G phones	Network identity, blacklisting, tracking
MEID	14 hex digits	CDMA devices (older)	Same as IMEI on CDMA networks
Serial Number	Varies	All devices	Manufacturer warranty, support ID

The IMEI is a network-level identifier — it is what carriers and governments use. The serial number is a manufacturer-level identifier — it is what Apple, Samsung, and other brands use for warranty and support. Both are important, but for theft reporting and network blocking, only the IMEI matters.