I am using RasPBX with Huawei E1752C USB dongle (identified as model E1752 by chan_dongle app).
I am running command dongle show device state dongle0 from cron and here are some interesting results (I grep “GSM Registration Status”):
Change: Unknown --> Registered, home network
Chance of status detected: 11-08-2022 at 20:30:01.
Change: Registered, home network --> Not registered, but searching
Chance of status detected: 12-08-2022 at 16:00:01.
Change: Not registered, but searching --> Registered, home network
Chance of status detected: 12-08-2022 at 16:01:01.
Change: Registered, home network --> Not registered, not searching
Chance of status detected: 12-08-2022 at 16:51:01.
Change: Not registered, not searching --> Registered, home network
Chance of status detected: 12-08-2022 at 22:37:01.
Please note that this is done by a small bash script, and the initial state in this script is “Unknown”.
Now… the problem is, that when the SIM card seems not to be registered on a network, I can actually accept calls, receive SMS and send SMS messages!
Why is that so?
Is it possible that GSM registration status is somehow flipping between 2G and 3G/HDSPA network and that SIM card looses connection to 3G, but it is still connected to 2G, however chan_dongle does not register this?
Any idea and/or solution?