Detect when an EXTERNAL_SIM is installed

Hi,

Is it possible to detect if a 3rd party EXTERNAL_SIM card is inserted before the Cellular connection is made? What I would like to do is default to the INTERNAL_SIM, unless I detect that an EXTERNAL_SIM is in the slot.

Thanks.

  • Chris

There is a SIM switcher (FSA2567MPXMLP) which picks which SIM is connected to the cellular modem module. I am not entirely sure why this prevents the use of the internal SIM if an external one is inserted though.

It doesn’t.
Nor does that switch itself select which SIM to use. That has to be done by the firmware.

When using the Boron LTE (u-blox SARA R410M-02B) you cannot switch between SIMs in software if an external SIM is installed.

  • No external SIM installed, internal SIM selected in software: works
  • External SIM installed, external SIM selected in software: works
  • External SIM installed, internal SIM selected in software: neither SIM is selected

This is a hardware problem in the modem itself and is not fixable.

The 2G/3G (u-blox SARA-U201) does allow switching between SIM cards in software only but there is no hardware SIM detect.

1 Like

Ok, good to know. My testing is showing the following:

Boron 2g/3g:

  • No external SIM installed, internal SIM selected in software: works
  • External SIM installed, external SIM selected in software: works
  • External SIM installed, internal SIM selected in software: works

Boron LTE:

  • No external SIM installed, internal SIM selected in software: works
  • External SIM installed, external SIM selected in software: works
  • External SIM installed, internal SIM selected in software: does not work

What I would like to know is if there is a way (maybe through AT commands) to detect if an EXTERNAL_SIM is installed, and the call Cellular.setActiveSim() appropriately? This would allow me to fail over to/from the Particle service.

Thanks

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