ST eSIM doubts (profile, pre-programming)

[JPehl.1]

Hi.

Currently we use SIM7000G and SIM7070G (GSM, NB-IoT, LTE-M, GNSS) modules from Simcom in our projects, using for authentication only a SIM holder with plastic chip, in the old way. We are starting to integrate the eSIM ICs on the boards, to use holder for plastic SIM + eSIM IC + dual SIM card analog MUX, I already did a layout including these 3 things, but still have doubts about the the eSIM.

I have sent this email do Simcom support:

"Hi, we would like to know if, for SIM7000G and SIM7070G modules, if they are compatible and can work with eSIM chip/IC like the ST4SI2M0020TPIFW of ST Microelectronics, we plan to use this one. Do I just need to connect the electronic signals of the SIM interface of the modules to the same named signals of the eSIM chip/IC?

I saw that in Brazil, for the newer smartphones integrating an eSIM, the network operator would generate a QR code to the user, who would scan it with the camera and then the smartphone would write informations in the eSIM chip. But how the same operation would work for IoT devices which uses Simcom modules? Will the modules maybe require firmware update to become compatible?

Can you give us a guide? The Simcom modules in question are the SIM7000G and SIM7070G."

Their answer was:

"Yes, the SIM7000G and SIM7070G modules are compatible with eSIMs of any brand.

When purchasing the chips, you will have to contact the manufacturer and provide the profile that you want to be installed on this eSIM. No modification to the modules firmware is required."

Then I sent back a second email:

"May I ask 2 question?

(1) In eSIM chip/IC, is there the need to write/program something on it before soldering it to the board/PCB? I mean a write/program done directly in the hardware, directly on the pins of the IC, using a specific tool to make this function.

(2) If the module (SIM7000G ou SIM7070G) be supplied, and having the cellular antenna and eSIM connected to it, is this sufficient to be able to install/write the profile in the eSIM through the cellular network?"

But they did not replied this second email. About question (1) and (2) above, could somebody from ST help me? These are doubts I have and searched a lot on internet and didn't found the answer.

How is the procedure to contact the eSIM manufacturer to install the profile?

Please, I would like a clarify about these questions.

Regards,

Jeferson.

[Agostino VANORE]

Hi Jeferson, thanks for your questions.

The ST4SIM part number (ST4SI2M0020TPIFW) you selected is already pre-programmed with a default (bootstrap) cellular connectivity from Truphone.

Truphone is ST authorized partner enabling our customer to the cellular connectivity.

So, the first step after the soldering the eSIM on your PCB, is to register it and enable connectivity with Truphone following the following procedure (https://www.st.com/resource/en/application_note/an5740-st4sim-with-truphone-connectivity--activation-procedure-stmicroelectronics.pdf).

The ST4SIM-200M is also compliant to the GSMA eUICC M2M standard and then it is also possible to switch operator remotely, but also in this case the management is done through the Truphone platform and it depends on specific agreement with upcoming operators.

Cheers,

Agostino

[JPehl.1]

Hi Agostino, thank you very much!

Considering I have a setup like below (IoT device), could you clarify how the eSIM exchanges informations with the Truphone? And if possible, a little more detailed?

[eSIM IC] <--1--> [SIM7070G] <--2--> [GSM/NB-IoT/LTE-M] <----> [Truphone]

1 - SIM card interface

2 - Radio frequency interface

Thanks in advance,

Regards.

[Agostino VANORE]

Hi,

concerning the SIM card interface, everything is regulated by the standards:

• ISO 7816 for the communication layer
• ETSI/3GPP for the application layer

Take also in consideration that the SIM is essentially 'slave' during the normal behavior answering to the commands received from the modem as specified in ETSI 102 221, ETSI 131 102 and so on.

After the authentication on Truphone network, the modem is allowed to use normal data channel through the defined APN.

Concerning the item 2, the SIM doesn't have any cellular radio interdace.

Hope this clarify your doubts.

Rgds,

Agostino

[JPehl.1]

Hi Agostino, thanks for your attention. 

I also shown this topic to another person from our company, from technical staff. We are still not convinced. 

Question (A): How the app (Truphone) will communicate with the eSIM to parametrize it? Since there is the modem between them? 

Question (B): Does it works this way? The app (Truphone) communicates with the modem, which in turn communicates with the eSIM. If the answer is yes, is it required for such operation (eSIM parametrization) that the MCU interact with the modem through AT commands? or such eSIM parametrization through Truphone is transparent to the MCU that is connected to the modem?

Regards,

[Agostino VANORE]

Hi,

according the ETSI standards, the telecom operators are allowed to access their own eSIM by remote.

The protocols define security and operation to modify files content and add/remove java card applet.

The modem receives command from network and do the forward to the eSIM through ISO interface.

That mechanism is transparent to the MCU.

Rgds,

Agostino

[JPehl.1]

Thanks very much Agostino.

Regards.

[FBert.6]

Hi,

I'm new on this forum.

At the moment I have connected the MCU to the SIM800F SIMCOM modem and I would like to implement this eSIM chip.

I think I understood everything but I still have a doubt: to get the ICCID for the first activation, do I have to make the Chip communicate with the MCU? Or can I make it communicate from the SIM800F modem?

Thank you

[JMarshall123]

AT+CICCID is the AT command you send the SIMCOMM module to return the eSIM ICCID