The essential information about communication with Cinterion modems

Communication mode

The modem provides two separate AT channels - "application", which is supposed to be used to control the modem, report unsolicited notifications etc., and "modem", which is supposed to be used for things like data transfer. There is also a NMEA channel for GPS. Channels can be assigned to UART (one channel at time), USB CDC-ACM (one channel at time), USB composite (multiple channels possible), or MUX on either UART or USB can be used.

The default communication mode of PHS8 is "application" on UART and "modem" on USB CDC-ACM. This means that with default config, notifications about incoming calls and messages are provided only via UART.

To change it into some better suited to our needs mode, AT^SDPORT is used. The value is stored, applied immediatelly and persistent between reboots.

To put all channels into USB composite device and disable UART, type:

AT^SDPORT=3

CAUTION: don't type AT^SDPORT=2 ("modem" on UART, USB disabled) without ability to talk to the modem via UART, because otherwise you won't be able to switch it back!

Other values include 4 ("application" on UART, "modem" and NMEA on USB) and 5 (NMEA on UART, "modem" and "application" on USB)

GPS

It's adviced to set the RTC correctly before attempting to use GPS, especially when wanting to use A-GPS.

Example: AT+CCLK="14/05/15,19:03:20"

To control the GPS engine, AT^SGPSC command can be used. TODO