eSIM Explained

eSIM Explained

eSIM Explained

Introduction to eSIM

eSIM technology essentially replaces the need for the distribution of physical SIM cards that allow devices to connect to mobile networks. Instead, the data stored on those SIM cards (represented by a coloured dot) is sent directly to the mobile device in a highly secure manner over the Internet.

eSIM Explained

Upon arrival into the device, this data profile is required to be stored securely, and for this purpose a secure chip, soldered into the device (called an eUICC) is used. This chip is able to store multiple profiles from different MNOs.

In order for the mobile network operator (MNO) to correctly bill a subscriber for mobile service use, they need to be sure that it is the subscriber using those services and not, say, a hacker. To do this, they share an identity (called the International Mobile Subscriber Identity or IMSI) and a cryptographic secret with the subscriber, both of which are later used to identity and authenticate that subscriber every time they use mobile services.

The SIM card is an ideal medium for sharing such information as it is portable and tamperproof, meaning the data stored on it cannot be read, which in turn, means the SIM card cannot be copied.

In addition, the SIM card is able to store other data and even applications. A SIM card from one MNO will have a different data profile to a SIM card from another MNO (signified by a different coloured dot).

Because the SIM card is also removeable, the subscriber can easily change from one device to another (subject to the new device having the same SIM form factor).

eSIM technology brings about numerous benefits, including:

  • New, smaller mobile device form factors that are too small to accommodate a physical SIM card
  • Even in larger form factors such as smartphones, space inside the device is at a premium – eSIM releases value space for other device functions or a larger battery
  • Mobile devices are far-easier made waterproof with the removal of the SIM slot
  • No more waiting for SIM cards to arrive in the mail or having to go to a retail outlet to get one – and no more troubles having the ‘wrong-size’ of SIM card
  • Fast and easy activation of mobile devices – devices can be connected to mobile networks within a minute or two, straight out of the box
  • A catalyst for Dual SIM technology in smartphones (see our whitepaper on this topic)
  • All the MNO costs and logistics of existing SIM card distribution disappear
  • A huge benefit to the environment given the reduction of plastic and chemical waste from billions of SIM cards every year
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eSIM provides a whole host of benefits in IoT too, including:

  • A soldered eSIM chip avoids problems with shock, vibration and humidity that come about with the spring connections of a removable physical SIM card
  • The IoT device is able to be hermitically sealed from its external environment whilst still allowing MNO change
  • Removes the requirement for many piles of SIM cards on the production line – enabling global distribution with a single SKU
  • Late stage provisioning is now possible, either on the production line, or even after the device arrives in-country
  • Change of MNO for an entire estate of deployed IoT devices can be performed remotely and automatically – no need to send out engineers to devices to swap out SIM cards

In order for a device to connected to a mobile network via eSIM, it needs to know the Internet address of the MNO’s subscription management platform (SM-DP+). The device also needs to have a unique reference to the eSIM Profile stored on that platform (Activation Code Token).

The most basic way is for these two items of information to be provided in the form of a QR code (Activation Code), which when scanned by the camera of the device, will cause it to reach out to the MNO and download the required eSIM profile.

For devices having no camera, this code can be manually copy pasted from an email or text message.

There is another activation method, called Discovery Service, where the MNO can target an eSIM profile to a particular device, which will automatically receive that profile a few seconds later, or as soon as it is next switched on.

For devices capable of running mobile apps, this looks to be a popular way for branded entities to activate devices – the app may also include plan selection and payment.

The de facto standard for eSIM technology is the GSMA Consumer eSIM specification.

You can find out more about eSIM here: https://www.gsma.com/esim/

And read the technical specifications here: https://www.gsma.com/esim/esim-specification/