Project status

### Works
- Dial number, accept incoming call, hangup
- DTMF tones
- USSD commands
- Simple SMS messaging cases

### Issues
- Airplane mode currently disables modem same as `mmcli -m any -d` does.

### Doesn't work:
- Concatenated (long) SMS
- SIM identification
- Data
- PIN / PUK entering (PIN must be disable prior to using)
