Ensuring Global Interoperability – Today and in the Future

Kathleen Knievel, Corporate Marketing Manager, COMPRION
Ensuring Global Interoperability – Today and in the FutureNowadays, everybody is using the smartphone for mobile services – be it for writing emails, checking the internet for a hip restaurant, staying in contact with friends, or finding the way to a holiday resort. We simply expect that all these services work – no matter where we are.

Only very rarely, we contemplate the effort it takes to get the technology up and running and make it globally interoperable – considering the huge amount of stakeholders involved. This can only be achieved by sufficient testing with globally binding technical and testing standards as well as reliable test equipment as the basis. SIM interface testing –COMPRION’s core competence for the past 20 years – plays a tiny, but essential part. The SIM card – as the secure token in the smartphone – is responsible for identification and authentication within the mobile network.

In the future, we will use more and more connected devices. Many of them will include a SIM card for mobile data connectivity. However, using regular SIM cards in cars, windmills, or traffic lights, would make it very troublesome to change the service provider (MNO) or in some use cases even to comply with official regulations.

Now, the industry is working on a new standard that helps the customer to change the operator easily without all the time and effort and the safety regulations: the eSIM – the embedded SIM. It has the same tasks as a regular SIM card but is permanently installed into any possible mobile device, allows changing the operator, and thus offers many other advantages. Every MNO has a different profile that needs to be brought to the SIM card. It contains the contract details of the end user and determines the behavior of the mobile device.

Advantages of eSIMs/eUICCs

  • Easy to change
    The effort of changing the operator subscription is reduced (no need to physically remove the chip card by getting the device back to a store) as it can be done remotely using the over-the-air interface.
  • Size
    The eSIM is smaller than a regular SIM card. The remaining SIM slot space can be used for other technologies (for example, a bigger battery).
  • Robustness
    The eSIM is extremely robust as it tolerates vibrations of machines and cars, and extreme temperatures, dust, vibrations, and humidity (thus, no more rusting as with the conventional SIM card slot).
  • Theft protection / security
    Conventional SIM cards used in traffic lights for example have been a popular target for theft – eSIMs are permanently installed and thus harder to steal.
  • Cost efficiency
    The production and distribution of eSIMs compared to regular SIMs is more cost-efficient as provisioning and personalization takes place at a late point in time.


SIM Provisioning Today

SIM Provisioning Today

Provisioning the SIM card nowadays involves many logistic and physical steps and companies. After the SIM card is manufactured, it needs to be personalized according to the MNO requirements. Then, the cards are distributed to the different MNO shops where they are activated. If a phone user wants to change the operator at a later time, the old card needs to be replaced by a new one and the whole card process starts from scratch. During all these steps, the safety regulations and administration efforts for the many involved companies are huge.

eSIM Provisioning in the Future

eSIM Provisioning in the Future

During its production process, the yet unsoldered eSIM receives a so-called “provisioning profile” by the eUICC manufacturer. It provides network connectivity for the mobile equipment in order to download the actual consumer subscription. This includes the file system, network access applications, and credentials as well as supplementary security domains (SSD) for third-party service providers together with their application. Depending on the implementation, the profile provisioning could also take place after the distribution.  Hence, the effective MNO is selected much later during the life cycle, in fact after delivery of the device, when it is put into operation for the first time. After this initial selection, there might be various re-assignments during the life cycle without having to replace the chip card. Creating new profiles or deleting old ones can be done on demand. An eUICC can even hold multiple profiles at a time, with only one single profile being active at any point in time. This active profile determines the behavior of the eUICC and thus the device.

Testing Now and Then – How to Meet the Challenges
Although this new technology has many advantages, it also faces big challenges when it comes to testing and making the technology available smoothly and reliably. As the SIM is permanently installed, it is difficult to access the card for testing.

When testing a regular unsoldered card, the SIM was inserted into a terminal simulator. The simulator sent commands to the card and the SIM had to react in a pre-defined way. When testing the mobile phone, its SIM interface was connected to a SIM simulator by help of a probe. Some of the mandatory tests that a mobile phone had to pass before receiving the type approval stamp involved a network simulator.


  • Access
    If a communication problem occurs, how to access the UICC when it’s permanently soldered into the device? Before, the old SIM was simply replaced by a new one. With an embedded SIM, the device with a permanently soldered UICC would be lost in the worst case.
  • Reliability
    How to make remote SIM provisioning reliable?
  • Future meets present
    How to assure that the old processes and technologies also interoperate in the new world?
  • More players – highest complexity
    In the new world, the mobile network operator (MNO) is not the only one involved in offering new services: providers of back-end server and service providers enter the game. The new roles need to be determined and matched. At the end, the technology still needs to be interoperable to be accepted, no matter how many players involved.
  • New players – additional testing effort
    In case of an eUICC used in a car, not only the card has to be tested, also the modem manufacturer embedding the eUICC and the car manufacturer who integrate the modem in the console.
  • The new world is just shaping
    Some standards – especially for consumer devices – still need to be developed. There are not many devices yet – so for testing it’s necessary to work with simulations.


In the new world, there are three main areas that have to be tested:

1. Card tests
The UICC itself needs to be tested before it is permanently soldered. These pure card tests according to standards from GlobalPlatform assure the basic card functionality (analog behavior, chip qualification).

The card profile provided by the Mobile Network Operator that contains the contract data has to be tested according to pre-defined SIMalliance standards. The profile influences the behavior of the mobile device.

2. Testing the eUICC in the mobile device in the network
Most UICC-related USIM/USAT tests are so-called combined device tests, meaning that besides the UICC interface, the air interface is also involved.

3. Remote SIM provisioning tests
Changing the operator subscription needs to be tested as well. It is important to test if the eUICCs can communicate with the RSP servers worldwide and that the device and eSIM combination performs the RSP procedures correctly. If a problem occurs while downloading a new profile to a new mobile device, for example, in a car, it won’t work in the new network. It’s possible that the whole mobile device or at least the communication module is broken and might even be a total loss.