What Is an IMEI Number? A Complete Guide to Mobile Device Identity

An IMEI number is one of the most important identifiers attached to a mobile phone. It helps distinguish one cellular device from another, supports network and manufacturer records, and can become essential when a phone is lost, stolen, insured, repaired or sold. Yet it is also widely misunderstood. Some people believe the IMEI is a tracking code that reveals a phone’s exact location to anyone. Others confuse it with a SIM number, serial number or mobile number.

This guide explains what an IMEI is, how it is structured, how to find it, how it is used, what it cannot do, and why every phone owner should keep a secure record of it.

What does IMEI mean?

IMEI stands for International Mobile Equipment Identity. It is normally a 15-digit identifier assigned to cellular equipment. The GSMA describes the IMEI as the electronic serial number used to identify a GSM-technology cellular device. A legitimate device should have a unique identifier unless it has been tampered with or incorrectly manufactured.

The key word is equipment. Your mobile number identifies the subscription or SIM relationship. The IMEI identifies the phone’s cellular equipment. If you remove one SIM and insert another, the phone number may change but the device IMEI normally remains the same.

Why mobile networks use IMEI numbers

A mobile network needs to know both who is connecting and what equipment is connecting. Subscriber information is associated with the SIM or eSIM. Equipment information is associated with the IMEI. This separation allows operators and authorized systems to identify a device independently of the phone number currently being used.

Depending on the operator, country and applicable rules, IMEI information may support:

• device identification on a cellular network;
• lost or stolen device reporting;
• network restriction or block-list workflows;
• fraud and insurance review;
• manufacturer, repair and warranty records;
• device registration and ownership documentation;
• used-phone due diligence.

An IMEI check is therefore useful, but it is not a complete certificate of ownership or safety. A buyer should combine an available registry result with the invoice, seller identity, account-lock status, carrier status and physical inspection. See the complete used-phone buying guide.

How an IMEI is structured

A standard IMEI normally contains 15 digits. Parts of the identifier are associated with an approved device type and an individual unit. The final digit is used as a check digit to help detect common entry errors. The structure is technical, but an owner does not need to decode it manually. The practical responsibility is to record the full number accurately and compare it across trusted sources.

When comparing a phone with its box or invoice, every digit matters. A one-digit difference means the identifiers do not match. That mismatch may have an innocent explanation, such as a replacement device or incorrect paperwork, but it should be resolved before a purchase or ownership claim is completed.

Single-SIM and dual-SIM phones

A single-SIM phone commonly has one IMEI. Many dual-SIM devices have two IMEIs: IMEI 1 and IMEI 2. Google’s official device guidance explains that dual-SIM phones can have one IMEI for each slot. Owners should record both identifiers where available.

This matters during a report because only recording one identifier may leave the second cellular identity undocumented. When registering a dual-SIM device with IMEI Alert, enter both IMEIs whenever the form provides that option.

How to find the IMEI

The exact menu differs by brand, but the common methods are straightforward:

1. Dial *#06#: many phones immediately display one or more IMEIs.
2. Check phone settings: Android devices normally show it under Settings > About phone. Apple lists it under Settings > General > About.
3. Check the SIM tray: some models print an identifier on the tray.
4. Check the original box: the retail label often includes the IMEI, serial number and model.
5. Check the invoice or operator record: some purchase and service documents include it.
6. Use the owner account: Apple or Google account records may help when the device is no longer available.

For brand-specific instructions, read how to find an IMEI on iPhone and Android.

IMEI versus serial number

The IMEI and manufacturer serial number are separate identifiers. The serial number helps the manufacturer distinguish a particular unit for production, service and warranty purposes. The IMEI identifies cellular equipment. A purchase record may contain both.

When documenting ownership, keep both identifiers. The IMEI is especially relevant to network and lost-device workflows, while the serial number can be important for manufacturer support. Neither should be treated as a password.

IMEI versus SIM, ICCID and mobile number

These identifiers serve different roles:

• IMEI: identifies cellular equipment.
• ICCID: identifies a SIM card.
• Mobile number: identifies the callable subscription number assigned by an operator.
• EID: identifies eSIM hardware on supported devices.

Replacing the SIM may change the ICCID and mobile number relationship, but it does not normally replace the phone’s IMEI.

Can an IMEI reveal the owner’s personal data?

The digits themselves are not a readable file containing the owner’s name, photographs, messages or passwords. However, an operator, insurer, retailer, authority or registry may have a separate record that associates a device identifier with a person or transaction. Access to such records should be controlled by law, policy and authorization.

This is why the complete IMEI should not be published casually. It is not a secret credential in the same way as a password, but it is a persistent device identifier and should be shared only for a legitimate purpose.

Can a phone be tracked by IMEI?

An IMEI is not a public GPS tracker. Entering an IMEI into a website cannot legitimately produce an exact live location by itself. Apple Find My and Google’s device-finding service use authenticated accounts, device settings, network connectivity and location technologies. Mobile operators and law-enforcement bodies may have additional lawful capabilities, but those are not public lookup services.

Be cautious of anyone who promises an exact live map after receiving only an IMEI and a payment. Review common fake IMEI tracking scams before sharing money, credentials or documents.

What is an IMEI block list?

A device may be reported to an operator, insurer or authorized registry after loss, theft, fraud or another qualifying event. Participating networks may then restrict the identifier. Coverage is not identical worldwide, and records do not always update at the same time. A device that works on one network or in one country may still have a problematic record elsewhere.

For a deeper explanation, read IMEI blacklist explained.

Can an IMEI be changed or cloned?

Legitimate owners should not modify an IMEI. Tampering can be illegal and may be used to disguise a stolen or counterfeit device. Two devices presenting the same identifier can indicate cloning, manufacturing error or manipulation. A buyer who sees mismatched or duplicated identifiers should stop the transaction until the issue is independently resolved.

Why record the IMEI before an incident?

After a phone disappears, owners often discover that the retail box is missing, the invoice cannot be found and the account record is incomplete. Recording the IMEI in advance makes reporting faster and more credible. Store it with the serial number, invoice, purchase date, model, colour and photographs.

You can also create a secure ownership record before an incident. Read why device registration helps before a phone is lost.

IMEI checks when buying a used phone

Before paying for a second-hand phone:

• display the IMEI from the phone itself;
• compare it with the box and invoice;
• check both identifiers on a dual-SIM phone;
• review any available lost, stolen or registry result;
• confirm that Apple, Google or manufacturer account locks are removed;
• test calls and mobile data;
• verify the seller and keep a signed receipt.

A clean-looking IMEI result is one part of due diligence, not a universal guarantee. Operator finance records, insurance claims and country-specific restrictions may exist outside a public platform.

What to do if a phone is lost or stolen

Use the official Apple or Google device-location service first, remotely secure the phone, protect important accounts, contact the operator and preserve evidence. If theft is suspected, follow local police-reporting procedures and do not confront a suspected person.

Keep the IMEI, serial number, invoice and incident details ready. Follow the lost-phone checklist or submit a structured report through IMEI Alert’s report-device form.

Practical privacy rules

• Do not post a full IMEI in public comments or marketplace listings.
• Do not send it to an unverified person promising tracking.
• Do not share account passwords or one-time codes with an IMEI service.
• Keep purchase and ownership documents in secure storage.
• When selling a phone, remove personal accounts and provide a proper receipt.

Key takeaway

The IMEI is a persistent identifier for cellular equipment. It helps networks and authorized organizations distinguish devices, and it supports ownership, reporting and used-phone checks. It does not by itself reveal live GPS location, personal messages or account passwords. Record it securely, use it responsibly, and combine any IMEI result with broader ownership and security checks.

Sources and further reading

• GSMA Device Check FAQs
• Apple: Find serial number, EID, IMEI/MEID or ICCID
• Google: Find device serial number and IMEI
• FCC: Protect Your Smart Device