February 01, 2024
Mobile device testing is key to ensure interoperability between device and network. An undetected interoperability issue can cause serious problems for the user or the network. That’s why the industry is running very comprehensive device conformance testing programs, e.g. according to GCF or PTCRB regulations.
For the proper behavior of the device, one decisive factor is the correct interaction between the baseband processor and the secure element - aka SIM card - used. Many interactions between the device and the mobile network are controlled or at least influenced by the SIM and the configurations it contains. This is what the USIM/USAT part of mobile device conformance testing covers. While in the past this was only tested with the plugged-in SIM card, the industry now also wants to perform such conformance tests based on the device’s eSIM/iSIM (more specifically, nrUSIM, i.e. non-removable Universal Subscriber Identity Module, regardless of whether remote SIM provisioning is supported as for eSIM/iSIM or not).
A new test specification for eSIM
3GPP already started working on USIM / USAT test specifications some time ago: 3GPP TS 31.127 (USIM) and 3GPP TS 31.117 (USAT). A noteworthy milestone was achieved in December last year: TS 31.127 was moved into “change control” mode. This means that the specification has reached a significant level of completeness, is published at the 3GPP web portal, and is waiting for test tools vendors to provide respective test solutions.
New test methods
In contrast to the previous USIM/USAT test specifications, which used the ability to connect a test solution to the existing terminal/card interface and observe the transmitted data, new test methods had to be developed that no longer rely on this physical connection:
- IMPLICIT testing: Configure eSIM profile, execute the specified test procedure; correctness can be verified on the radio interface.
- TOOLKIT EVENT based testing: Use a dedicated SIM applet and specific events to trace the eSIM/device communication; correctness of data and commands can be verified from the eSIM/iSIM.
- SEAMLESS testing: Device/chipset manufacturers implement logging of the data intended to be transmitted over the eSIM/iSIM - baseband processor interface, correctness of data and commands can be verified from an exported log file.
PROs and CONs for the test methodologies
The reason why different test methodologies have been defined is that the methodologies all have their different PROs and CONs:
- IMPLICIT testing:
- PROs: no need for any special support from the device or its eSIM/iSIM – hence universally applicable.
- CONs: only a small scope can be tested, and results are less reliable.
- TOOLKIT EVENT based testing and SEAMLESS testing:
- PROs: allow a broad testing scope with reliable results.
- CONs: require that device/chipset vendor (for SEAMLESS testing) or the eSIM/iSIM vendor (for TOOLKIT EVENT based testing) must fulfill certain prerequisites. Which vendor will do so is not entirely clear at the moment. Also, the implementations will vary across different vendors.
The consequence is that each player – whether eSIM/iSIM, device, chipset or module-manufacturer or provider of test solutions such as COMPRION, needs to define its product strategy in this situation with some unknown factors.
You want more information?
At COMPRION, we have a plan and stick to our commitment to provide a comprehensive solution that delivers reliable results. Get a more comprehensive overview on this topic in our recent webinar.
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