SIM hot swapping - what is the expected behavior?

Nick B nickberry17 at
Mon Sep 24 23:32:39 UTC 2018

Good day,

I have a dual SIM hardware setup with a MC7430 in QMI mode where both SIMs are attached to the SIM 1 & SIM 2 pins on the modem.  I do not have any ability to switch SIMs using GPIO or anything in between.

I have been playing with modem manager to switch the SIMs using the —command parameter like so:

—command=AT!UIMS=n where n can be 1 or 0, as I have only 2 SIMs.

The issue I am facing and what my question is about is this:

When I issue the AT!UIMS=n command, and check it with AT!UIMS? the SIM index seems to switch immediately, but it appears to me that I have to restart modemmanager to use the SIM. (Do I?).  I don’t actually have to reset the modem, I have checked.  The strange part follows: if I then try to enable the modem with -e, modem manager loses the modem until I restart modem manager.   I have waited up to 5 minutes to see if modem manager finds the modem again but it will not.

I’m happy to script this activity, but I would like to get some clarification as to what the expected behavior is in case I am doing it wrong.  Perhaps if I switch it to MBIM mode?  Is there any way to get the SIM to show up as a SIM object with an index number in mmcli with this setup?



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