Sierra module mc7304 - sim problem

Hello,
I am facing an issue for some time. After the device has been running for a long/short time, the SIM card is suddenly no longer visible by ModemManager. The status indicates sim-missing, even though the card is physically inside. A physical reboot of the power supply/system reboot generally does not help, but there have been cases where, for example, a reboot helped after 20 times. The same applies to restarting via AT commands sent to the modem - AT+RESET, AT+CFUN=0/1 or resetting the usb port into which the modem is plugged (usb_modeswitch) also usually does not help, but there have been cases that, for example, after 20 times it helped. So far the only method that works 100% is that the customer turns off the device → pulls out the sim card, puts it back in → turns on the device. The problem comes back all the time. This is not a single case, the same thing happens on more than a dozen devices.

Any help or suggestions would be appreciated.
Thank you.

could it be some instability hardware issue on the SIM slot?

Could be, but we have a lot of same devices (with sim cards from various providers) and nothing happens. It only happens to one customer.
At the beginning he used to have microSim card, but after that they switched to miniSim card which perfectly fits into the slot.

Seems to be sim slot problem

Thank you for your suggestions.
Also one more thing, when the problem occurs, some AT commands return - CME ERROR: 13 which is → sim failure
When SIM is not inserted into the slot it return CME ERROR: 10 which is → sim not inserted
But in general, I am aware that error 13 may follow that previously the sim card was detected and while working suddenly stopped. Am i right?

Error 13 could be some signal problem

Do you mean line signal problem on sim card? It is possible for it to move slightly and that is why?

I don’t know, probably you need tp use oscilloscope to check

Okay, i think the sim missing problem is related to moving it a bit in a SIM slot. This customer has also Quectel modules and they are also have sim missing problem but i can just type mmcli -m $n --reset and works like a charm.
So I dig a bit and found that quectel ec25 has SIM hot swap feature enabled by default. Then i found that MC7304 also has sim hot swap feature but only on certain firmwares. In my case i have FW -SWI9X15C_05.05.58.00 r27038 carmd-fwbuild1

When i run ModemManager it stuck on:
<<<<<< translated = FAILURE: InvalidQmiCommand
ModemManager[19096]: [1740986686.693302] Couldn’t initialize interface: ‘Firmware interface not available’
ModemManager[19096]: [1740986686.693524] SIM is missing, but this modem does not support SIM hot swap.
ModemManager[19096]: [1740986686.694177] Extended signal information reporting disabled
ModemManager[19096]: [1740986686.694767] Couldn’t finish initialization in the current state: ‘Modem is unusable, cannot fully initialize’

Do you know firmware for mc7304 which has sim hotswap feature?

here says you can use this in AT!CUSTOM:

Yes, by default it is enabled in my case. Because it does not show in !CUSTOM? command:


When I set it to ‘3’ for example (which disables both UIM’s) it shows up as 0x03. So default 0x00 does not show up if I understand correctly.
So to be sure i set SIMHOTSWAPDIS to 0 ( response is OK), but it still show as I described above → " ModemManager[19096]: [1740986686.693524] **SIM is missing, but this modem does not support SIM hot swap."

then probably this is sim slot problem