What is an IMEI Number? Why Does It Matter for eSIM Users?

Whenever you buy a smartphone or any phone, you have to buy a number that allows you to connect with the network via the carrier. Here comes your IMEI number the moment you buy your device, and you use it to communicate whether you are checking device authenticity, unlocking a phone, or activating an eSIM.

Now, to understand the IMEI number you need to know that it is an important number in terms of mobile security and connectivity. In this blog, you will learn what an IMEI number is, how to find, check, and verify it, IMEI blacklisting, and its importance for eSIM activation.

What is an IMEI Number?

The International Mobile Equipment Number, or IMEI, is a 15-digit code that is assigned to your mobile device as an identity. Just as you have your ID with you, so does your phone. Like you, ID is used to trace your accounts and everything, same as the IMEI number is used by:

• Carriers, Manufacturers, and even law enforcement agencies to track, block, and verify your device.
• To stop reselling stolen phones by IMEI blacklisting.
• eSIM activation and network compatibility issues.

Understanding the Structure of an IMEI Number

IMEI numbers are very special and unique. They are not just some regular numbers written randomly or like a serial number. The IMEI number follows a special format. For example, to break down an IMEI number we will take a number like 356789101234567. Every digit has a purpose, see this:

TAC (Type Allocation Code)

• Digits: First 8
• Purpose: Tells about the phone model & manufacturer

Serial Number

• Digits: Next 6
• Purpose: Unique to the specific device

Check Digit

• Digits: Last 1
• Purpose: Validates the IMEI using a security algorithm

Why it Matters: The Type Allocation Code (TAC) assists in detecting counterfeit or cloned devices, while the check digit serves to guard against IMEI fraud.

Why is an IMEI Number Important?

Well, how important is your National ID to you? Same way IMEI is very important for:

• Device Identification: Every mobile on this planet has a unique IMEI.
• Security & Anti-Theft Measures: Stolen Devices can be blacklisted and blocked from mobile networks.
• Device Authentication: Used for eSIM activation and network registration.

Pro Tip: Before purchasing a second-hand mobile phone, check its IMEI number to see if it's blacklisted.

How to Find Your IMEI Number?

Every company has different ways to check IMEI number, I will tell you all ways possible:

How to Check IMEI on iPhone?

• Dial *#06#, a universal code to check IMEI number instantly.
• Tap Settings> General> About> Scroll to IMEI.
• If you have the device box, an IMEI number is printed on it.

How to Check IMEI on Android?

• Dial *#06#, a universal code to check IMEI number instantly.
• Tap Settings> About Phone> IMEI Information.
• Some Android phones have IMEI printed on the battery side or the box of the device.

How to Check IMEI using USSD Code?

Unstructured Supplementary Service data or USSD is a code in GSM protocols that enables service without needing a data connection. Dial *#06#, a universal code to see your device IMEI in an instant.

How to Use IMEI Number for Device Tracking?

You have often heard about lost and found devices. Have you ever wondered how this process works? It involves tracking your device using its IMEI number. If you lost your device, you need to:

• Report your IMEI number to your carrier to block network access.
• Police through Geo fencing and tracking apps can track your device by using IMEI.
• You often see locator services in Apple and Samsung that use IMEI-based tracking.

Pro Tip: Try to register your IMEI number with your carrier before travelling to avoid network restrictions abroad.

Can You Change or Fake an IMEI?

Besides its illegal in many countries, it could be possible.

• Many unauthorised services claim that they can change IMEI number but doing so is a fraud.
• If the IMEI number changes the device get blacklisted, so no network on the device.
• It's upto manufacturers that they can change IMEI, if they repaired a device.

Verdict: For any reason, do not engage in such activity of changing your IMEI. You can face legal consequences or might lose your device network functionality forever.

IMEI Vs. Serial Number: What’s the Difference?

Purpose

• IMEI: Identifies the device on mobile networks
• Serial Number: Manufacturer’s internal tracking

Where It’s Used

• IMEI: Mobile carriers, eSIM activation, blacklists
• Serial Number: Warranty, device repairs, inventory

Uniqueness

• IMEI: Unique globally
• Serial Number: Unique within the manufacturer’s database

Pro Tip: Filling an Insurance Claim? Your provider asked you for both IMEI and Serial Number.

What is an IMEI Blacklisting?

Blacklisting an IMEI number means to block the device from using any network connection. This is usually done when someone loses their device or has it stolen.

• Whenever IMEI is blacklisted, the carrier shares it with the global databases like GSMA.
• If you buy a second-hand blacklisted phone, you can not use connect to most network carriers.
• To save yourself from IMEI fraud, check the blacklist status before buying phone.

How to Check if an IMEI is Blacklisted?

You can use online tools like:

• IMEI.info
• Carrier IMEI checker tools
• GSMA blacklist databases

IMEI and eSIM: How are they Connected?

eSIM is the new game, and whenever you want to activate your eSIM, your IMEI verification is necessary.

• eSIM compatible devices have multiple IMEI numbers.
• For eSIM activation, carrier networks verify IMEI numbers.
• Whenever you activate eSIM, try to provide the eSIM slot IMEI, not the physical SIM one.

Pro Tip: If you got a blacklisted IMEI phone your eSIM activation is not possible.

How to Unlock a Phone using an IMEI Number?

Sometimes you need to switch carriers, and to do this your IMEI is required to unlock:

• Request an Unlock code from carrier.
• Make sure IMEI is not blacklisted.
• Once unlocked, request approved, you can switch to any carrier or eSIM provider.

Best For Travelers: Having an unlocked phone means you can use local eSIM cards or eSIMs abroad.