SIM versus eSIM

SIM versus eSIM

If you have ever traveled internationally, or watch spy movies then you may be familiar with SIM cards. They’re that little piece of plastic in your phone that you must replace with another carrier’s as soon as your plane lands—or remove from your phone so movie villains can’t track you. “You mean the one I always lose?” Yes, that one. A SIM card is basically a tiny piece of silicon that securely identifies your mobile device on the network, so when you switch carriers you have to switch SIM cards, pretty simple.

However, many people have constant issues with their SIM cards.  For example, your phone consists of a screen, a battery and a lot of silicon. So why then do you need to plug another tiny piece of silicon into your phone to get it to work? Surely these tech companies can just dedicate some hardware to doing the SIM’s work and then you don’t have to look for a paperclip to open your phone’s SIM slot every time you travel or are being pursued by henchmen. Well that’s exactly what an eSIM does. eSIM, or embedded SIM, has been in the works for many years, but at Computex 2017 Microsoft finally announced its commitment to making it happen. The reason being that it fulfills part of their goal of having “always connected PCs” that are constantly connected to the cloud. For this purpose Microsoft is collaborating with the big names in silicon, Qualcomm and Intel, and with device manufacturers like Lenovo, HP and ASUS to make this happen.

As the SIM card evolves there are three definitions to keep in mind:

1. Traditional SIM: This is the small removable smart card. It stores the operator defined profile which enables identification and authentication on the network. It can only store one profile from one operator.
   
   
2. Remote Provisioning: This is the ability to change the profile on a deployed SIM without having to switch out the SIM hardware. It can be used both with the traditional SIM form factor, like the Apple SIM, or with the eSIM form factor. It has more memory so that multiple profiles can be saved on the same SIM. You can then swap between the stored profiles without having to change SIM cards.
   
   
3. eSIM: Short for embedded SIM, this is a SIM that is physically integrated into the device and cannot be removed or replaced. The eSIM can either be added as a separate discrete component on the device PCB, or integrated into the communications processor silicon.

The only way to change the operator profile on an eSIM is with remote provisioning, so when referring to the eSIM, the ability to perform remote provisioning is often implied. With all this talk about SIM hardware you may be wondering why you need hardware for a SIM at all? Can’t you just save the operator and account information in the device’s memory and use it to authenticate the device on the network? Yes, that’s called a Soft SIM. A Soft SIM has no hardware layer and performs all its functions in software. The problem is that it loses the security provided by a dedicated piece of cryptographic hardware and making hacking of the profile a possibility.

So what benefits do the eSIM revolution offer for the consumer and M2M IoT markets? From the table below we can see that most consumer devices will benefit from the smaller size of the eSIM. This is especially true for smart watches and other wearable devices. Convenience in switching carriers or profiles will also come as a relief to consumers who are tired of swapping out SIM cards. The biggest benefit will be for companies using cellular for M2M communication. Imagine a company has devices deployed all over the country; if they decide to switch carriers then changing out the SIM cards would be a very expensive process. With remote provisioning this expense is eliminated. For these reasons, many are looking forward to seeing the eSIM become the standard for both consumer and M2M applications.

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