Hi Mychaela,
On Wed, Feb 03, 2021 at 11:01:19PM -0800, Mychaela Falconia wrote:
My ideal dream SIMs for running my own GSM/2G network (a network whose sole purpose is to provide service to classic GSM/2G phones) would be those that have only the classic SIM application, and NO USIM or ISIM. And I would really like for USIM and ISIM to be truly-truly Not There, rather than just hidden from EF_DIR.
In theory, you should be able to remove the respective applications from most java based cards with the right credentials via SCP02. Did you try?
I am currently in negotiations with Grcard in China, who are telling me that they can supply me with such SIMs, and at an affordable price too, without a cost-prohibitive MOQ.
sysmocom can certainly also provide such cards, should you have a related requirement. It requires creating a card profile without ADF.USIM + ADF.ISIM, which certainly can be done. I think the cards will still react to APDUs with CLA != 0xA0, but you would not have any ADF.USIM or ADF.ISIM present.
One clear disadvantage of using SIM without USIM functionality even on a 2G radio network is that you can never use mutual authentication between network and phone (which is a pure protocol related aspect, so it could be implemented in any phone/baseband whose software can be modified - including FreeCalypso.
Regards, Harald