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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

In a previous post I wrote about one mobile network operator in Germany now being on air with LTE with 65 MHz. So far, network operators have been in the comfortable position to add additional spectrum to increase their network capacity. But this game will come to an end pretty soon!

Continue reading How Much “Air” Is There Still For LTE?

Almost exactly a year ago I wrote a post about how much LTE capacity network operators in Germany have on air. One network operator had a total of 2x 50 MHz of LTE on air spread over 3 frequency bands. One year later, things have again improved.

Continue reading One German LTE Network Operator Now On-Air with 65 MHz

In the previous part of this series I gave a quick introduction to the difference between today’s handling model of a physical SIM that the user can insert in any device and embedded-SIMs to which subscription information can be downloaded. In part 2 I’ll now give a high level overview of how this download process works in practice and how the user remains in charge of when and how often he wants to change the subscription information in the eSIM.

Continue reading Embedded-SIM Intro – Part 2 – SIM vs. eSIM User Scenarios

I’m not and I never was never a great Apple fanboy. When I was a teenager in the second half of the 1980s, the Apple Macintosh still cost several thousand euros and was hence far beyond what I could afford. Like most, my computing world was that of Commodore, Atari and others who offered affordable computers for the likes of me. The PC with Windows followed my home computing phase which in turn was followed by Linux and Open Source. In other words, there was no space in my world for the always much more expensive Apple computers at any time. But obviously they played and are still playing an important role in the computing space so I decided to read up a bit on the history of the first Apple Macintosh.

Continue reading Book Review: Revolution In The Valley

One thing that has been surprisingly absent on this blog so far was a discussion on how embedded-SIM cards work. Call me a traditionalist, as for me, the SIM card in its current form has been the greatest invention since sliced bread and so I saw no reason to change the concept. This is because a removable SIM card allows me to use my mobile network subscription(s) with any device. I can move my subscription, i.e. the SIM card quickly from one device to another and, equally important, I can put in another SIM card in my main device, e.g. to use a local SIM card while traveling. The device belongs to me and there is no lock-in of a device to a specific network operator. Does this also work with eSIMs (or with eUICCs, to be exact), i.e. when the SIM card is soldered in place and thus no longer removable and subscriptions have to be downloaded?

Continue reading Embedded-SIM Intro – Part 1 – High Level Model

Recently I wanted to have a closer look at how authentication works for the XCAP protocol that is used in VoLTE by mobile devices to control things such as call forwarding settings. At first I thought that the topic is so far off the beaten path that I need to have a look in the specifications right away. But I gave Google a chance and was quite positively surprised that there’s a ton of information out there that is much easier to digest than going to the specs right away.

Continue reading VoLTE – GBA Authentication For XCAP

Recently my firewall at home had a bit of a hick-up and decided to change the rule to forward a high external TCP port number to port 22 of one of my servers into a 1:1 mapping of that port instead. As I was about to go into a long meeting I couldn’t immediately react and fix things so for a couple of hours the SSH server of that machine was accessible from the Internet via its native port – with interesting results.

Continue reading Port 22 Anecdotes