# Multi-IMSi vs eUICC

## Introduction

Multi-IMSI technology is essential for cellular IoT providers that plan on deploying globally or creating mobile applications. Multi-IMSI is an abbreviation for Multiple International Mobile Subscriber Identities. An[ IMSI](https://www.simbase.com/iot-glossary-dictionary/imsi) is a key component of a Subscriber Identity Module (SIM), which is stored on a SIM card. Each one allows a device to connect to a limited number of networks. It enables subscribers to switch carriers as needed and connect to significantly more networks.

After reading this article you’ll understand:

* [What is IMSI](#what-is-imsi)
* [What is a Multi-IMSI](#what-is-a-multi-imsi-sim)
* [Know about Multi-IMSI benefits](#benefits-of-multi-imsi)
* [What is eUICC and eSIM](#euicc-and-esim)
* [Learn about eUICC benefits](#benefits-of-euicc)
* [Differences between eUICC and Multi-IMSI](#euicc-vs-multi-imsi)
* [How to choose best option for you](#technologies-for-flexibility)

## What is IMSI?

To understand what Multi-IMSI is, you first need to know what IMSI is.

An International Mobile Subscriber Identity (IMSI) is a unique 15-digit number that identifies every mobile network user globally. The IMSI is divided into two parts. The first part is a six-digit or five-digit number based on the North American or European standards, respectively. The initial set of numbers identifies the mobile network operator in a specific country with whom the user is subscribed to. The network operator allocated the second part of the IMSI number to uniquely identify the subscriber.

The IMSI number is not always printed on the SIM card and you would have to look deep in the settings for it to show on your device. The IMSI is stored in the Subscriber Identity Module (SIM) inside mobile devices and is sent by the mobile device to the appropriate network in which the SIM is associated. When a mobile device is powered on, the device indicates its IMSI number to the associated cellular network to perform a location update - this is referred to as the attach procedure. This update is also carried out when a[ handover](https://sprout-kale-7ct5.squarespace.com/iot-glossary-dictionary/handover) occurs to another[ base station](https://sprout-kale-7ct5.squarespace.com/iot-glossary-dictionary/base-station) (Cell Tower). This update is received by the corresponding visitor location register which updates the[ home location register](https://sprout-kale-7ct5.squarespace.com/iot-glossary-dictionary/home-location-register-hlr) of the new location. When the mobile device is powered off, an IMSI detach procedure occurs. This shows that the device is no longer connected.

## What is a Multi-IMSI SIM?

Now that you know what an IMSI is, a multi-IMSI is simply a SIM with more IMSIs. That means that a SIM card can decide which IMSI to use in any country. Having few IMSIs can help you get better data costs and coverage based on the country used. Simbase leverages the technology to provide great pricing and coverage on a single SIM. We check each country and select the best operators based on costs and the number of networks. When a SIM card enters a different country, it automatically selects the best IMSI.



<figure><img src="https://2653492456-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FYV3zfJTXLR73Umqnex88%2Fuploads%2FcLZ3qDBY6xV1VjEksIg8%2FSingle%20IMSI%20SIM%20vs%20Multi%20-IMSI.png?alt=media&#x26;token=b5b4e7dd-2070-4926-a382-b2ad89c813fa" alt=""><figcaption></figcaption></figure>

## Benefits of Multi-IMSI

You don’t notice any differences looking at a multi-IMSI SIM, but there are plenty of benefits:

1\. Better coverage. A single network provider might not have agreements around the world with all the operators and even if they do, they might not offer the best rates.

2\. National Roaming. You cannot access multiple networks in the country where the SIM card originates from. You might have noticed that your regular phone SIM card is attached to your provider and you cannot use other networks in your area - Multi-IMSI fixes that.

3\. Better rates. You can get better rates both locally and globally based on the provider you choose to use.

4\. Worldwide access. Simbase offers cards with multiple IMSIs that, if needed, provide access to different countries and continents at a better rate. This means that a single SIM card is enough for global deployment.

## eUICC and eSIM

eUICC is a new technology that offers the ability to change service providers over-the-air (OTA). That means you do not have to switch operators by replacing the card, but you can do it remotely which is convenient as you do not have to store these profiles on the card itself and these profiles can be changed anytime depending on your needs.

There is some confusion between eUICC and eSIMs. As some refer to eSIM and eUICC (Embedded Universal Integrated Circuit Card) interchangeably. eUICC is the programmable part of the SIM, while eSIM is embedded directly into a device without the ability to remove it. It can have over-the-air support, but it is not something that you could use in a regular SIM card slot. eUICC can be removable (just like any other regular SIM card) and non-removable (embedded) SIM cards.



## Benefits of eUICC:

1. **Remote Provisioning**: eUICC SIM cards allow for remote provisioning of mobile network operator profiles. This means that users can switch between different network providers without physically changing the SIM card. It offers greater flexibility and convenience, especially for travelers or users in areas with limited network coverage from a single provider.
2. **Global Connectivity**: With eUICC SIM cards, devices can be pre-programmed to connect to multiple networks in different regions or countries. This enables seamless international roaming and ensures that devices remain connected even when transitioning between coverage areas or encountering network outages.
3. **Scalability and Future-Proofing**: eUICC technology allows for over-the-air updates, enabling operators to remotely update SIM profiles, add new services, or enhance security measures without requiring physical access to the SIM card. This scalability and flexibility ensure that devices remain compatible with evolving network technologies and service offerings.

## eUICC vs Multi-IMSI

<figure><img src="https://2653492456-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FYV3zfJTXLR73Umqnex88%2Fuploads%2FaqOY0lkQRlTEYYxP33qa%2FMulti-IMSI%20vs%20eUICC.png?alt=media&#x26;token=186f69ea-22fc-4da8-bdb2-7c4199744b96" alt=""><figcaption></figcaption></figure>

Both eUICC and Multi-IMSI are great technologies that enable the option to change coverage, pricing and MNOs.&#x20;

While eUICC can be a bit more complex to implement, it provides additional flexibility in the sense that the profiles on the card can be changed over the air - which means that providers can be changed without physically swapping out the cards, which is not the case with Multi - IMSI.&#x20;

eUICC can also provide better performance regionally as generally the profiles are optimized for specific regions (e.g North America, Europe, Oceania etc). The reason for this is that once the profile is loaded onto the card, it simply works without additional complexity. Multi-IMSI on the other hand,  it has pre-loaded multiple profiles for different regions and the change between the profiles happens automatically as the SIM Travels from one region to another. Although this can be slightly more convenient, at times, profile switching can take longer than expected.&#x20;

These are different technologies that address different business needs and depending on your requirements, you may have to choose which one works best for you.&#x20;

## Technologies for flexibility

While both Multi-IMSI SIM and eUICC serve as viable solutions for addressing connectivity needs in IoT deployments, the choice ultimately depends on the specific requirements and objectives of the project. While Multi-IMSI SIMs offer amazing coverage and automatic profile switching, eUICC provides unmatched flexibility and future-proofing capabilities. Regardless of the path you choose, at Simbase we got you covered. Get in touch with one of our IoT experts if you’d like to find out more.
