How does a global IoT eSIM work?

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The hype around global eSIM solutions for IoT use cases continues to grow. And there are a number of solutions out there for you to choose from. However, it’s not quite as simple as it sounds. Different providers will have very different methods for providing a global eSIM service.

Now, before we proceed let’s start with a definition. What is eSIM? Well the answer to that is a bit long and complicated in itself (and for a more detailed explanation check our “what is eSIM” blog) but for the purposes of this blog when we say eSIM we are talking about an eUICC SIM with the ability to switch between network providers remotely. 

A global eSIM solution should offer the ability to switch between multiple network operators without requiring a physical SIM swap allowing simple and scalable global deployments on a single SKU. Pelion’s preferred method of achieving this is via GSMA’s accredited remote SIM provisioning (RSP) process (you can read about the spec over on GSMA’s website). However, there are other ways to achieve similar benefits which we will also cover in this blog.

The three primary methods for this kind of single SIM global connectivity solution are:

      1. GSMA accredited eSIM allowing the remote provisioning of any operator profiles OTA to an eUICC SIM

      1. Multi-IMSI which allows multiple identities to be stored on a single eUICC providing the ability to switch between a pre-allocated set of operator networks

      1. An eUICC SIM with a roaming profile only (this isn’t really eSIM at all but sometimes gets confused)

    In our opinion only number 1 represents a true eSIM service that provides a properly future-proof and simple solution for build once, deploy anywhere global connectivity. This blog explains why.


    Global IoT eSIM – GSMA 


    In a GSMA-compliant implementation of eSIM for global deployments the SIMs will usually come preloaded with some kind of roaming profile (commonly referred to as a bootstrap profile) to allow it to get connected initially wherever it is deployed or manufactured. Often all this first profile provides is the connectivity to be able to take advantage of the GSMA remote SIM provisioning (RSP) process, allowing your to add a more appropriate profile that offers better, more price-competitive coverage in your deployment country.

    The combination of this bootstrap which is then used to provision a better profile from a more local operator is what global eSIM looks like today. Whilst this “better profile” might not be a truly country specific local profile it will still provide better options than a single profile roaming SIM. For example, you might be deploying in France but the profile you provision will be from an Irish operator with great roaming coverage in France. It’s still a good solution, just not perfect.

    A common question that we get asked when discussing eSIM solutions with our customers is “can I have local eSIM profiles in every country?”

    The short answer is no (not yet). But you can get quite close to it.

    With the GSMA eSIM standard it is technically possible to provision a local operator profile to your SIM in any country in the world. However, practically speaking this is not what eSIM solutions look like today. You can still get global coverage on an eSIM, just how that is made possible can vary.

    The primary reason you can’t get local profiles in every country is that not all operators actually offer their profiles for use as part of an eSIM service with the ability to remotely provision them to any eUICC SIM. Even if they did, a provider of this kind of service would have to have dedicated agreements and technical integrations with each individual operator in every single country which is just not practical.

    However, it is possible today to have multiple eSIM profiles across key regions internationally each with the ability to roam onto local networks, thereby offering something close to “local profiles in every country”.

    For example, at Pelion we have multiple eSIM agreements with multiple operators across the world. All of these profiles have either roaming capabilities or broad international networks meaning that we can provide local network connectivity on a “semi-local” profile. This means if your deploying in, for example, North America and several countries in Europe, we can offer you a choice of North American operator profiles and a choice of European operator profiles. This gives you great coverage at a much better cost than a “global roaming” solution could.

    The advantage of eSIM service based on GSMA’s standardised remote SIM provisioning (RSP) process is that we can remotely provision any eSIM profiles to any eUICC SIM at any time, and as we add new operator eSIM profiles to our catalogue (a process that is constantly happening) that new profile can then be made available to all our existing eSIM customers. The whole thing is standards based meaning greater interoperability, greater flexibility, and proper future-proofing of your deployments which the alternatives can’t offer to the same degree. 


    Global IoT eSIM using Multi-IMSI

     The next and increasingly common method is using multi-IMSI. A multi-IMSI SIM is a SIM with multiple different operator IMSIs (or identities) pre-provisioned onto a single SIM. Now, this can be a nice solution. It allows you to switch between those pre-provisioned IMSIs as required and provides a lot of comparable benefits to a GSMA spec eSIM solution. However, it also has a few downsides…

    It’s not standards-based, so different providers all have different ways of doing it which can create problems if you are working at a large scale across multiple providers. Not all multi-IMSI solutions have the ability to add/remove new connectivity offerings to that SIM over-the-air (OTA) and those that do can be much more complicated in practice than they may first appear. Whilst it can work, it’s certainly not as “elegant” as the GSMA-accredited methods. It is also likely to become less and less popular as the current GSMA RSP specs evolve to be even better suited to IoT use cases. 

    Overall, a multi-IMSI solution might end up just adding complexity to the process, requiring additional software on the device or SIM to manage the profile swaps, or being restricted to working with the 3-4 IMSIs already on the SIM.


    Global IoT eSIM – Roaming Only


    Although this one is not technically an eSIM solution sometimes there can be confusion if an eUICC SIM is used as part of a deployment. The point being, deploying on an eUICC SIM does not necessarily mean your provider can actually offer the associated services to take advantage of that technology as part of a full eSIM service. There is a lot of dedicated infrastructure required to enable the remote SIM provisioning (RSP) process that takes time, money and specific expertise to put in place. If your provider doesn’t have all this in place then deploying on an eUICC with a single roaming profile on it isn’t much different from deploying with a standard UICC roaming SIM.

    The problem with a normal roaming SIM is that you are relying on the underlying operator maintaining their roaming agreements with all of their existing partners and you are also relying on the locations in which you need roaming coverage maintaining a roaming-friendly policy. This last point is definitely not guaranteed as evidenced by Turkey who recently ended all roaming access meaning any SIMs connecting to a local Turkish network but on a roaming SIM was permanently left without connectivity.

    Roaming agreements also need to have IoT use cases pre-agreed between the various connectivity providers involved otherwise you can run into issues using roaming connectivity for a use case that doesn’t fall under the pre-agreed permissions. In this scenario, it’s entirely possible to end up in trouble.

    If the SIM is an eUICC then technically it’s possible to provision a profile to it down the line even if it wasn’t deployed with all the infrastructure in place at the time but this is pretty impractical in reality. The whole point of eSIM is to add flexibility without adding too much complexity. Hence, it’s much better to just find a provider who already has all the supporting infrastructure in place and take advantage of their existing service.


    Picking the right solution


    The closing message would be that not all offerings branded as a “global IoT eSIM solutions” are the same and it is important to make sure you know what your priorities are before getting into an “eSIM” conversation. Think about things like device life span, likely deployment locations, device mobility, budgets etc. first. Once you are having conversations make sure you are absolutely clear what you are getting. You also need to be confident this solution is going to fit your requirements not just now, but over the lifespan of your device taking into account the possible risks presented by market dynamics changing.

    Of course, it goes without saying if you want some advice about what solution we think best fits your application reach out to us or take a look at the various resources we have available here, on

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