SIM on chip

11 thoughts on “SIM on chip

  1. Hello,

    we use GE865 with a normal SIM card holder and it works fine. Now we have changed to a SIM on chip and it don’t work any more.

    Is there any additional detail we must aware?

    A hint in this matter is highly appreciated.


    Thank you. 

    1. In what way is not working? What SIM on chip, how is connected, are all integration specifications applied?



  2. SIM don’t answer.

    From T-Mobile Germany

    Connection is made like a normal SIM card holder, just SIMIN(on module site) is direct grounded and the I/O from SIM have an external pull up resistor from 47k according to the documentation from SIM on chip manufacturer.

    Yes all specifications are applied I hope.

    1. I think a direct investigation on hardware signals can give some answers. What voltage levels is using that chip?


          1. This is typical SIM on chip connection. In this case SIMIN is connected to the chip.


            What is AT+CPIN? response ?  set AT+CMEE=2 first.


            Please use an oscilloscope as suggested by Cosmin to verify SIM lines (VCC, IO, CLK…).

            With AT#SIMDET=0/1 you can simulate SIM removal/insertion.

          2. Problem solved. We removed the suggested pull up resitors. Now it works. Thank you for assistance.