Wireless • Last Updated 9/29/2023

What is IMSI switching, and how does it work?

IMSI switching allows devices to connect to networks across the globe. Learn about IMSI switching, its benefits, and use cases.


By Kelsie Anderson

SIM card connecting in different countries via IMSI switching

An international mobile subscriber identity (IMSI) is a unique identification number assigned to every SIM card. Mobile networks use this number to identify and authenticate a subscriber and route calls and data to the correct destinations.

An IMSI is made up of 15 digits, composed of three parts:

  1. Mobile Country Code (MCC)—Three-digit code that identifies the country where the SIM card was issued.
  2. Mobile Network Code (MNC)—Two- or three-digit code that identifies the mobile network operator within that country.
  3. Mobile Subscriber Identification Number (MSIN)—Unique nine- or ten-digit number that identifies the individual subscriber.

IMSI Diagram

The IMSI is stored on the SIM card and is used to authenticate a device with the mobile network when the device is switched on. Once authenticated, the device can make and receive data connections—or calls, in the case of a mobile phone—on the mobile network.

What is IMSI switching?

In an increasingly interconnected world, businesses must create products that can be used nearly anywhere. Especially for any device that connects to a mobile network, manufacturers need to ensure the SIM cards in their devices can access multiple networks. That’s where IMSI switching comes in.

IMSI switching involves changing an IMSI to enable the same SIM to connect to different mobile networks in different countries or regions. This capability is convenient for people who travel frequently and need a mobile connection in many countries. However, it’s particularly useful for IoT devices that are designed to operate globally and require reliable network connectivity across different geographic locations.

Why is IMSI switching critical for the growing IoT market?

IoT devices are typically designed to use a specific mobile network for connectivity. However, device manufacturers sell themselves short if they limit their devices to one network. Devices often need to operate in different countries or regions where the designated network may be either unreliable or unavailable. IMSI switching allows these devices to connect to different mobile networks with different IMSIs, providing both devices and manufacturers with a broader range of connectivity options.

IMSI switching also enables a more efficient manufacturing model, as businesses can assemble devices in any location with a single SIM. Manufacturers can rest assured that mobile wireless connectivity will be available regardless of where an operator turns on their IoT device. So rather than producing multiple versions of the IoT device, each with a different operator SIM depending on the final destination of the device, a single SKU approach is possible.

IMSI switching can be implemented on traditional physical SIM cards and embedded SIM (eSIM) technology. eSIMs are programmable SIM cards that can store multiple IMSIs and be remotely provisioned over the air (OTA). These capabilities allow IoT devices to switch between different IMSIs and mobile networks without requiring physical SIM card replacement.

Overall, IMSI switching for IoT devices is a useful technique that enables reliable connectivity across different regions and networks. It helps to ensure IoT devices remain connected and functional, which is essential for applications such as asset tracking, remote monitoring, and smart city infrastructure.

How does IMSI switching work?

As the name implies, IMSI switching involves changing the IMSI of a device to enable it to connect to different mobile networks in different countries or regions. The process of IMSI switching involves the following steps:

  1. A device is equipped with a SIM or eSIM, which contains multiple IMSIs for different mobile network operators.

  2. When the device is turned on, the SIM is notified of the country code visible on the radio interface, which allows it to activate an IMSI based on a pre-determined lookup.

  3. The SIM sets the chosen IMSI as the active one and initiates the network authentication procedure.

  4. If the device detects that the network connection is poor or unavailable, or if it needs to operate in a different country or region, it disconnects from the current network and reconnects to the new network using a new IMSI.

Benefits of IMSI switching

IMSI switching can provide several advantages for businesses that rely on mobile connectivity. Below, we’ve outlined some of the key benefits.

Increased connectivity

IMSI switching enables devices to connect to multiple mobile networks at competitive rates, providing improved connectivity and coverage across different regions and countries. More coverage helps businesses maintain reliable connectivity for their devices, even in areas where their designated network may be unavailable or unreliable.

Cost savings

By allowing businesses to use local networks instead of roaming on their designated network, IMSI switching can help save costs. The ability to switch to another network can reduce the cost of data usage and roaming charges, resulting in significant cost savings.


With the flexibility of switching between different mobile networks or service providers as needed, businesses can better adapt to changing market conditions, customer requirements, or regulatory environments.

Enhanced performance

IMSI switching can improve the performance of mobile devices by enabling them to connect to the network with the best signal strength and quality. Using the most effective available network can result in faster data transfer rates, reduced latency, and improved overall device performance.

IMSI switching use cases

With all the benefits IMSI switching can provide, you might be wondering how your business can leverage it to enable reliable and cost-effective mobile connectivity for your devices. Below are some of the most common use cases for IMSI switching.

Global asset tracking

IMSI switching can be used in asset tracking applications to enable devices to connect to multiple mobile networks across different regions and countries. The ability to connect anywhere ensures businesses can track their assets in real time, regardless of their location or network conditions.

Fleet management

In fleet management applications, IMSI switching can enable vehicles to connect to multiple mobile networks and ensure reliable connectivity for GPS tracking, telematics, and other applications. Connecting to multiple networks can help businesses optimize their fleet operations and improve driver safety and performance.

Remote monitoring

IMSI switching can be used in remote monitoring applications to enable devices to connect to different mobile networks and provide real-time data on metrics like environmental conditions, energy usage, or equipment performance. Access to this type of data in real time can help businesses optimize their operations and reduce downtime and maintenance costs.

Smart city infrastructure

In smart city infrastructure applications, IMSI switching can enable devices to connect to different mobile networks and provide real-time data on traffic, public safety, or environmental conditions. With this data, cities can improve public services and reduce costs by optimizing resource allocation and improving overall efficiency.

Industrial IoT

IMSI switching can be used in industrial IoT applications to enable devices to connect to different mobile networks and provide real-time data on production processes, machine performance, or environmental conditions. Understanding their operations on a granular level can help businesses optimize their operations and reduce downtime and maintenance costs.

Stay connected

Modern consumers expect convenience and constant connectivity. To stay competitive, manufactures need to ensure their connected products, apps, and devices can access a network from anywhere. And businesses that want to compete globally need access to real-time information from their equipment and devices regardless of location.

Telnyx SIM cards offer secure global connectivity, coverage on over 400 networks in over 180 countries, and the ability to configure SIMs OTA via an API. For organizations that need direct connections to their corporate networks, Telnyx also offers Private Wireless Gateways for even greater security.

Sign in to your Telnyx account (or create one) to purchase a SIM card. Or contact our team of experts to learn how our eUICC SIMs can help you connect anywhere.

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