Category: Uncategorized

Out of curiosity I tend to make a Wifi and cellular network scan when I am at places where I think I might find interesting configurations. When I was recently at a location that deployed Cisco Aironet Wifi Access points I was surprised to find an information element in the beacon frames that contained information about the number of clients connected and the system load (amount of time the access point found the channel busy).

Continue reading Wifi QBSS Load Element Shows Number of Connected Devices

It is obviously a must that any SIM card works in any cellular mobile device. By and large that works pretty smooth today. There is rigorous testing in place and I only know a few cases where SIM cards and devices did not harmonize and software updates were required to fix the issue. In the eSIM world where the user can’t remove the SIM card anymore but downloads a virtual SIM (a Profile) to a mobile device, interoperability is just as important. So how is this done in practice?

Continue reading Embedded-SIM Intro – Part 7 – Interoperability

When the Raspberry Pi came out it was a game changer as for the first time a cheap and easy to use Linux based board with lots of connectivity became available to the masses. Last week I read about a new Arduino board with a Sigfox chip that could be another game changer.

Continue reading An Arduino Board with Sigfox + 2 Years Connectivity for 50 Euros

Wow, this is already part 6 of my introduction series on embedded SIM cards and it’s not going to be the last, there are still a few topics left. Today, a few words about what are referred to as ‘companion’ devices.

Continue reading Embedded-SIM Intro – Part 6 – Companion Devices

After reading Andy Hertzfeld’s book about Apple and how the first Macintosh came to be in the first part of the 1980s, I thought it would be a good idea to get a perspective of the same time frame by someone working in another computer company. So my choice fell on “The Home Computer Wars“, written in 1984 by Michael Tomczyk.

Continue reading Book Review – The Home Computer Wars

For device manufacturers one of the main advantages of an embedded SIM is that it requires much less space than the slot required for a removable SIM, even when it is a nano-SIM (4FF). But just how big are eSIMs that are soldered on the circuit board? Many pictures on the web seem to be inaccurate to the extreme…

Continue reading Embedded-SIM Intro – Part 5 – eUICC Size

A couple of day ago, I read that Netflix now also supports video streaming in Firefox on Linux via Google’s DRM Plugin. I was delighted because I’ve been using Chrome so far which is by far not my first choice. But how good is it in practice, especially on older hardware?

Continue reading DRM Playback Performance – Chrome vs. Firefox

After introducing the eSIM (eUICC) Remote Service Provisioning (RSP) concepts in the previous 3 posts of this series it’s now time to have a look at the security implementation. Security is obviously of paramount importance in the process as the virtual SIM that is downloaded contains the identity (IMSI) of the user and the secret key used for authentication and generation of encryption material. If these two pieces were ever stolen in the RSP service chain it would be the greatest possible disaster for mobile network operators.

Continue reading Embedded-SIM Intro – Part 4 – eUICC Provisioning Security

A couple of posts ago I linked to an interesting post on another site about the XCAP protocol used in VoLTE networks for managing things like call forwarding settings. At the time I was a bit in a hurry so I bookmarked the site for further investigation. When I came back a couple of days later I noticed that “Real Time Communication” by Karel Berkovec is a treasure trove when it comes to intro articles on ‘all things IP’ in wireless operator core networks. Highly recommended!

In the previous two parts of this series I’ve taken a look at how the eSIM and downloading virtual SIM cards into devices compares to using physical SIM cards today. Now that the general concept is clear, let’s name some of the components involved which will help a lot when reading the standards documents GSMA SGP.21 and SGP.22. Continue reading Embedded-SIM Intro – Part 3 – Acronyms