Remember the old days when switching mobile carrier took weeks or using network services abroad required getting a local SIM? Well, with the advent of eSIM all such problems are soon going to be a thing of the past.
But before diving into seeing how eSIM can cause such a disruption, let’s first address some basic questions.
What is a SIM and how does it work?
A SIM or Subscriber Identity Module is a small integrated-circuit in the form of a chip that is used to perform all network related operations. These operations can be anything from calling, messaging, browsing the internet etc. In a nutshell, a SIM is the most important component when it comes to performing most of the operations on the phone.
Over the years, the size of the SIM has kept getting smaller, resulting in four form factors, 1FF or FULL-SIM, 2FF or MINI-SIM, 3FF or MICRO-SIM, 4FF or NANO-SIM. Irrespective of the different form factors, the size of the memory has always been the in the same range (8-256KB).
A SIM memory is mainly used to store information required for authentication and proper functioning. It has also been used to store Contacts in the past. But with the various cloud services available, that option seems obsolete.
Two of the most important pieces of information stored on a SIM is the IMSI number and the Authentication key.
An IMSI or International Mobile Subscriber Identity is a 15-digit number stored on a 64-bit field that is used to determine the subscriber’s mobile network and country of operation. It is one of the most valuable information and thus needs to be secured from any misuse. For this reason, another identity called the TMSI or Temporary Mobile Subscriber Identity is used instead.
Ki or Authentication Key is a 128-bit value which is present on a GSM SIM and used for the authentication process. It is unique for every SIM and is also present on the carrier’s database.
For the nerd inside you, here’s how the authentication process works:
- At first, when the device is turned ON, the IMSI is obtained from the SIM and passed on to the mobile network for access and authentication. This process may sometimes require a PIN.
- Next, the mobile operator looks for the IMSI and its associated key (Ki) in its own database.
- Now a random number (RAND) is generated and signed using the key (Ki) associated with that IMSI to generate a new Signed Response (SRES_1) along with a key (Kc).
- The operator sends the random number (RAND) to the device where its own key (Ki) is used to sign and generate another Signed Response (SRES_2) along with a key (Kc). This is then sent back to the operator.
- Finally, at the operator’s end, both the responses, SRES_1 and SRES_2 are compared to find a match. If found, the SIM is authenticated and can be used to perform communications in the future. In order to make this communication secure, it is encrypted using the key (Kc).
What is eSIM and how is it different from a physical SIM?
An eSIM or embedded SIM is a small chip embedded on the motherboard of the device which cannot be changed or swapped out, thus defeating the entire purpose of the SIM slot on the device. It is very small as compared to a nano-sized SIM card, which makes it easier to be included in smaller devices. Also, since they are embedded into the motherboard and no longer require a SIM slot, a lot of that space can be utilized in other ways.
An eSIM is very different from a physical SIM in the sense that it allows storing multiple network profiles, which make porting to a different network much simpler than before. Also, switching to a country’s local carrier as soon as you land in one is more convenient now than ever before. There are a lot of companies that have started providing such services. One of them is GigSky which allows you to switch to one of the supported network carriers of the visiting country. And the best part about these services is that they can be performed remotely from the device itself, and no longer require you to visit a store. This would save a ton of money which the network providers would otherwise levy on as roaming charges.
Who is using eSIM?
Lately, there has been a lot of buzz regarding the use of eSIM. Though the number of devices that use eSIM is only a handful, manufacturers like Apple, Google and Samsung have started implementing it on some of their devices.
In the case of Apple, the Series 3 Apple Watch is one of such devices that uses eSIM. It is required to perform seamless operations between the watch and the iPhone. To make that happen, the watch needs to be on the same network as the iPhone, thus allowing access to all the information present on the iPhone. However, this functionality is limited to certain network operators as of now.
Another use case of the eSIM is in iPad, where you can switch to a local network if you find yourself in a no Wi-Fi region. There aren’t a lot of carriers providing such services at the moment, but the count is soon going to increase as more devices start using eSIM. In both the used cases, the eSIM talked about is Apple’s own proprietary version of the eSIM called the Apple SIM.
Before Apple, Samsung was the first to implement eSIM on its second-generation smartwatch, called the Gear S2. Along with a bunch of changes that were made to this model, one of the most prominent change was the implementation of eSIM, which made switching carriers simpler than ever before.
On the other hand, Google introduced eSIM with some of its Pixel 2 phones in the US. However, that only works if you are a Project-Fi subscriber, where the built-in SIM would be used to authenticate to the supported carriers of your choice.
Apart from its use in phones, watches and other electronic devices, eSIM can also be used in IoT (Internet of Things). As for things to work in IoT, inter-connectivity between devices plays a very important role. For this purpose, eSIM would be the best solution considering its smaller form factor and the ability to remotely switch network profiles.
Let’s consider an example, say there are few devices, all on the same carrier, X. After a certain period of time, there arises a situation where the carrier is changed to Y. In such a situation, eSIM would make things simpler because of its ability to switch network profiles remotely. Thus, resuming the services as before.
With so many advantages over a physical SIM, one thing is for sure, the eSIM is here to say and make an impression in the telecommunication industry sooner than later.