See: BM818 Modem Firmware version
you maybe using the newest firmware using the commands shown whats your output?
In the terminal:
mmcli -L
then with output … /Modem/1…
mmcli --modem=1
Output:
firmware revision: MPSS.J0.2.0.2.c1.1-0032-9607_GENNS_PACK-1 1 [Feb 25 2019 01:00:00]
Which is the newest firmware for my US based modem as of Feb 2023.