Update:
I booted Megi's multi-boot to an old rev. of Mobian and updated my modem firmware:
mmcli -m any --command='AT+QGMR'
response: 'EG25GGBR07A08M2G_30.006.30.006'
So I guess it worked, but the phone still doesn't work. Guess I'll have to explore and research various settings to set and change.
I booted Megi's multi-boot to an old rev. of Mobian and updated my modem firmware:
mmcli -m any --command='AT+QGMR'
response: 'EG25GGBR07A08M2G_30.006.30.006'
So I guess it worked, but the phone still doesn't work. Guess I'll have to explore and research various settings to set and change.