IMEI or International Mobile Equipment Identity is one of the many unique identifiers associated with mobile phones. While other identifiers like IMSI, MSISDN and ICCID are linked to the SIM card, IMEI is connected to the mobile device itself. With the increasing trend of having the eSIM capability within mobile phones, it is becoming common to see dual SIM phones with one physical SIM slot and one embedded SIM slot.
A mobile phone has one IMEI number per SIM slot, so if you have a dual SIM phone, it will have two IMEI numbers: IMEI 1 for the first SIM slot and IMEI 2 for the second SIM slot. The IMEI number is a 15-digit code that is always unique which means a dual SIM cell phone has two unique IMEI numbers.
Why your dual-SIM mobile phone has two separate IMEI numbers
Dual-SIM phones are of two types, Dual SIM Dual Standby (DSDS) and Dual SIM Full Active (DSFA). With two SIM cards inside, a dual-SIM phone can use separate SIMs to register on two separate networks while using two unique IMEI numbers, one for each SIM connection.
The purpose of an IMEI number is for your mobile operator to know exactly which device is trying to access the mobile network. This information is required for the registration of the device on the network. The mobile phone communicates with the mobile network through the SIM card, which connects the device to the network and allows it to register. A mobile phone has a separate identifier for the SIM card called IMSI (International Mobile Subscriber Identity), which can change depending on the SIM but the IMEI for the device stays the same. Imagine if your phone gets stolen and someone replaces your SIM card with their own SIM. While an IMSI cannot help in that situation because it is linked to the SIM, the IMEI number can inform the network which device is being used. The mobile phone will communicate its IMEI number as soon as it connects to the mobile network, irrespective of which network it is on or which country it is in. The database where all IMEI numbers are stored is called Equipment Identity Register (EIR), which is part of a mobile core network. Dual SIM mobile phones are of two key types: DSDS and DSFA. Dual SIM Dual Standby (DSDS) only allows one active SIM card at a time, i.e. only one SIM can communicate at a time. Dual SIM Full Active (DSFA) allows both SIMs to be active simultaneously. With two different IMEI numbers, the same dual-SIM mobile phone can simultaneously register on two separate networks using two unique IMEI numbers.
What does an IMEI number look like?
IMEI stands for International Mobile Equipment Identity, and it is a unique 15-digit number assigned to every SIM-enabled mobile cellular device, including mobile phones, tablets, mobile broadband routers, smartwatches and IoT devices. Dual-SIM phones have two separate IMEI numbers.
IMEI is a device-specific number that is not linked to the SIM card but to the actual device. It is programmed into the device by the manufacturers, and only the device manufacturers are authorised to assign this number. Changing this number is called “unblocking, ” a criminal offence under UK laws. Below is a screenshot of what an IMEI number looks like.
How to find IMEI 1 and IMEI 2 on your dual-SIM mobile phone
The quickest and most effective way to find IMEI numbers on your dual SIM phone is to type the sequence *#06# on the dial pad of your mobile phone. As soon as you have typed this sequence, both IMEI numbers, IMEI 1 and IMEI 2, will be displayed on your mobile phone screen.
Nowadays, many new mobile phones have dual-SIM capability allowing you to use two SIM cards in one phone. In most cases, one of the SIM slots is for a physical plastic SIM and the other for an eSIM or embedded SIM. Irrespective of the number of SIM cards a phone can support, as soon as you type the sequence *#06# on the dial pad of your mobile phone, all IMEI numbers will be displayed on the phone screen.
How to find IMEI 1 and IMEI 2 in your phone’s Settings menu
The quickest way to check the IMEI number is to use the sequence, but in smartphones, including iPhone and Android phones, this information can also be found by navigating to the device information area.
On your iPhone, go to Settings > General > About
Step 1 – Locate the ‘Settings‘ icon and tap on it
Step 2 – Go to ‘General‘
Step 3 – Tap on ‘About‘
Step 4 – Locate your IMEI number by scrolling down to the area which shows IMEI, ICCID and other information.
On an Android phone, go to Settings > About Phone
If you have an Android phone, the Settings menu can look different depending on your phone manufacturer. However, generally, if you go to your phone’s Settings menu and tap About phone, you can find all the necessary device information, including both IMEI numbers, IMEI 1 and IMEI2. If you have an Android tablet, you can use the same process. In mobile phones with removable batteries, the IMEI number can be found at the back of the phone behind the battery area.
How to check IMEI on smartwatches and routers?
If you want to check the IMEI number for a mobile broadband router, it is usually printed on a sticker on the device. You can also check the IMEI number by logging into the router settings through the software (GUI) provided by the device manufacturer. Alternatively, you can use the web interface to access the device settings page by typing the IP address of the router (usually printed on the router, e.g. 192.123.1.2) into a web browser when physically connected to the router via a cable.
For smartwatches, it depends on the manufacturer. For example, in Apple Watch, the way to access the IMEI number is by going into Settings > General > About.
When might you need the IMEI number?
Suppose your mobile phone is locked to a specific mobile network, e.g. Vodafone, and you want to put a SIM card from another operator, e.g. EE. In that case, you need your device details so that your current operator (Vodafone in this example) can unlock your phone. The mobile operator whose network your phone is locked to will ask you for the IMEI number(s) alongside other details so that they can identify your phone and unlock it. IMEI number can also be used to protect your phone from being misused if stolen. If a mobile phone is lost or stolen, you should immediately contact the mobile operator so they can block the phone on your behalf. I have written a post on how IMEI numbers can be used to track mobile devices to help you understand the applications of IMEI numbers.
Here are some helpful downloads
Thank you for reading this post. I hope it helped you in developing a better understanding of cellular networks. Sometimes, we need extra support, especially when preparing for a new job, studying a new topic, or buying a new phone. Whatever you are trying to do, here are some downloads that can help you:
Students & fresh graduates: If you are just starting, the complexity of the cellular industry can be a bit overwhelming. But don’t worry, I have created this FREE ebook so you can familiarise yourself with the basics like 3G, 4G etc. As a next step, check out the latest edition of the same ebook with more details on 4G & 5G networks with diagrams. You can then read Mobile Networks Made Easy, which explains the network nodes, e.g., BTS, MSC, GGSN etc.
Professionals: If you are an experienced professional but new to mobile communications, it may seem hard to compete with someone who has a decade of experience in the cellular industry. But not everyone who works in this industry is always up to date on the bigger picture and the challenges considering how quickly the industry evolves. The bigger picture comes from experience, which is why I’ve carefully put together a few slides to get you started in no time. So if you work in sales, marketing, product, project or any other area of business where you need a high-level view, Introduction to Mobile Communications can give you a quick start. Also, here are some templates to help you prepare your own slides on the product overview and product roadmap.
As an expert in mobile technology and telecommunications, I've been deeply involved in the field for several years. I've extensively studied the intricacies of mobile device identifiers, network protocols, and the evolving landscape of cellular networks. My expertise encompasses the understanding of unique identifiers like IMEI (International Mobile Equipment Identity), IMSI (International Mobile Subscriber Identity), MSISDN, ICCID, and their functionalities within the realm of mobile devices and networks.
In the world of mobile communication, the IMEI serves as a pivotal identification code uniquely associated with a mobile device. Unlike identifiers tied to the SIM card such as IMSI or MSISDN, the IMEI specifically pertains to the device itself. Over time, I've closely monitored the evolution of mobile phones, including the emergence of eSIM capabilities, and how it influences the presence of dual SIM slots with distinct IMEI numbers for each slot.
Dual-SIM phones come in two primary types: Dual SIM Dual Standby (DSDS) and Dual SIM Full Active (DSFA). Each type utilizes the IMEI numbers to facilitate communication on separate networks simultaneously or one at a time, depending on the phone's capabilities.
The IMEI number acts as a crucial identifier for mobile operators, aiding in device registration on networks. This number remains consistent for the device regardless of the SIM card changes, distinguishing it from IMSI, which varies with each SIM card.
The storage repository for all IMEI numbers, known as the Equipment Identity Register (EIR), resides within the mobile core network. Dual-SIM phones leverage these IMEI numbers to register on distinct networks concurrently or individually, depending on the phone type.
A typical IMEI is a 15-digit unique identifier programmed by manufacturers exclusively for each device. Changing or tampering with the IMEI is unlawful in many jurisdictions and is referred to as "unblocking" under UK laws.
Discovering the IMEI numbers on a dual-SIM phone is conveniently achieved by dialing *#06#, which displays both IMEI 1 and IMEI 2 on the device screen. Alternatively, accessing the Settings menu on smartphones like iPhones or Android devices provides detailed device information, including the IMEI numbers.
For devices like smartwatches and mobile broadband routers, finding the IMEI number may involve checking stickers on the device or accessing the router's settings via the software interface or web browser.
The necessity for the IMEI number arises in scenarios such as changing mobile operators or reporting a lost or stolen phone, where mobile operators use this identifier for unlocking devices or blocking stolen phones from misuse.
Understanding the significance of IMEI numbers is crucial in various aspects, including device security, network identification, and compliance with network regulations.
In summary, the IMEI serves as a fundamental identifier for mobile devices, ensuring network registration and security while distinctly differentiating devices in a rapidly evolving mobile communication landscape.
If you're seeking further resources or information to delve deeper into mobile communications, I've curated eBooks, slides, and templates tailored for beginners, students, professionals, and those seeking a comprehensive understanding of cellular networks and mobile technology.
