IoT devices and SIM card remover tool

What is eSim? And how does it impact IoT?


eSIM and SmartSIM for IoT has changed the way CIOs and CTOs use cellular for their deployment and connectivity strategy. If you’re evaluating cellular as a backup for your primary connection, manufacturing a new IoT device, or taking a more comprehensive strategy, the carrier-first process of finding the best solution is no longer necessary.

Not everyone realizes how important the Subscriber Identification Module, or SIM card, is in the processing of making calls and transferring data traffic. In my long mobility and IoT career, clients have been regularly surprised to know my go-to hack to fix cell connectivity issues is simple: I pull out the SIM card, check for damage, and if fine, wipe and reinsert. People are more surprised when it often fixed the issue. The SIM card is your identity on the network, and a poor connection between phone and SIM can suspend critical functions.

Moving from SIM to UICC

The SIM card is essentially a little computer with an OS, processor, memory, and file folders. These are all housed on the little gold section of the card, known as an Integrated Circuit (IC). Every IC has a unique Integrated Circuit Card ID or ICCID, but that isn’t the only identifier a carrier uses to locate you on a network. Other identifiers, including MCC, MNC, MSIN, MSISDN, MEID, IMEI are used in conjunction with the ICCID.

Over the years, there have been many enhancements to the IC, including memory, security capability, and processor efficiency.  Today, we’re moving away from the traditional SIM cards in favor of Universal Integrated Circuit Cards (UICC). A UICC has multiple applications, including USIM, which takes on the traditional aspects of identifying the subscriber on the network. You can think of it as the younger, better looking, more in shape brother of SIM, or a SIMbling. (I’m so sorry)

What does the IMSI do?

The IMSI or International Mobile Subscriber Identity, technically a combination of the MCC,, MNC and MSISDN defines the country and mobile network or carrier the subscriber belongs to. Early SIM cards could only hold a single IMSI, so changing carriers involved swapping the new carrier’s SIM card into an (unlocked) device. 

The advantage of the UICC was how it allowed multiple IMSIs to be programmed on the same SIM card.  While that was a step in the right direction however, the first version of this design was limited to factory programming. Without the ability to be reprogrammed over the air, (OTA) usefulness was limited for an obvious reason: Major carriers weren’t incentivized to put competitor’s IMSI on their SIM cards to make switching carriers easy.

This development did allow for Mobile Virtual Network Operators (MVNO) on SIM cards that were able to connect to multiple carriers. Until that point, most MVNOs were companies like Cricket or Boost. Before they were bought by major carriers, they would wholesale purchase from a single carrier to offer voice, messaging, and data services. As the number of data-specific IoT devices grew, we started seeing MVNOs focus solely on data services. They would program multiple IMSIs on their SIM card to allow the device to connect to the network that was strongest at that particular location.

eSIM and SmartSIM for IoT: what you need to know

When looking at eSIM and SmartSIM for IoT, you will hear about the eSIM, SmartSIM, OneSIM, SingleSIM, or Global SIM. Depending on the company marketing these, there may be slight changes in the way they utilize the Multi-IMSI capabilities, so it is important to understand which one meets your IoT needs. 

What makes these a game changer for IoT is that not only do they utilize multi-IMSI, but they can also be reprogrammed over the air. When paired with an MVNO with wholesale options from hundreds of carriers across the world, this dramatically changes how you can use a device.

eSIM makes IoT coverage more robust

Some of these MVNOs work with over 600 carriers across the globe, in most countries, multiple carriers are available.  The major carrier networks have great coverage these days, but gaps are to be expected. In many cases, you can’t know which carrier is best at each location until you test it out, which presents a challenge for IoT devices that need to work everywhere and have unstructured deployment. 

With an eSIM, not only can the IoT device automatically connect to the strongest available network at a given location, but if that network drops, the device will reconnect to any additional network with sufficient strength. 

With eSIM, you can send out the same kitted IoT solution to all locations, knowing all devices will automatically determine which network is best. Your IT team can manually rotate through what networks the devices have access to on a case-by-case basis, if necessary.

eSIM for international. 

With 600+ carriers, eSIM and SmartSIM for IoT doesn’t just impact the United States. IoT devices will automatically connect to the network that has the best coverage at that location in over 200 countries worldwide. Using eSIM for international deployment is also a huge advantage, as it can be less expensive and have fewer usage restrictions and limits than roaming.

Chris Moeller of 3 Tree Tech
Chris Moeller

Chris Moeller is a 5G and IoT researcher at 3 Tree Tech. If you want to integrate IoT technology into your tech or need mobility infrastructure help, he’s willing to lend you his big brain. Reach out!

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