I am using EM7565 with 01.08.04_GENERIC firmware/PRI. My findings are:
when both left and right slots have SIMs, using AT!UIMS command can switch among them successfully (if AUTO-SIM is enabled, firmware/PRI will be automatically switched over as well)
when only one slot has a SIM, after system reboots ModemManager can find and make user of the SIM to setup data session.
However, if using the UIMS AT command to change to the empty slot, then using the command to change back to the slot with a SIM, ModemManager will always report SIM is missing
It seems to me that using the UIMS AT command to switch to an EMPTY slot will make the modem in a state unable to handle further UIMS AT command any more.
Also, the qmicli --uim-get-card-status command will only report status for the currently activated slot, is there a way for me to tell the SIM status in another, un-activated slot?