>> Huawei doesn't support CIND indications, so use CSQ
>> naturally the response from modem is not according to standard:
> is this true for all Huawei modems?
CSQ is not unsolicited, so you'd need to poll it. Not a good idea.
>> ofonod: < \r\n^BOOT:38645652,0,0,0,87\r\n
>> ofonod: < \r\n^RSSI:23\r\n
I suggest you simply support this ^RSSI notification, it looks like it has the
same 0-31 range as CSQ. Also, sometimes values from vendor-specific commands
differ from CSQ, so if a query of ^RSSI is supported, use that.
Actually I didn't check that. I'll investigate more.
ModemManager has done more work integrating ppp devices, poking around there
can get you some hints.