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Gsm in multiplex mode (GSM 07.10)


I’d like to use gsm modem in multiplex mode to make a voice call and send data on the internet at the same time.The problem is that PPP connection needs a SerialPort (phisical port) while I need to pass to it a serial virtual channel…
How can I solve the problem?


I don’t think MUX mode will work on NETMF. Unless GHI changes the PPP implementation so you can redirect PPP input and output.

Most modems have 2 or 3 hardware serial ports so you can AT, GPRS and VOICE or SMS all at the same time.


This came up before and maybe added in future but MUX is not supported fro now


Bummer. The Ublox GPRS modules allows you to connect a Ublox GPS directly to the GPRS over I2C.

The main application then accesses the GPS via one of the multiplexed channels on the GPRS.

The nice this about this is that the GPS is then in assisted mode, pulling almanac data from the net via the GPRS, with no coding or input from the main application. All just automatic.


Can you post some link to usb gprs-voice modem with such feature,please?

Thanks in advance.


I was talking about a serial modem. F.e. the Siemens MC75 has 2 serial ports. (It also has a USB port)

You can keep the first for AT commands, starting voice calls, etc. While GPRS works on the second port.

At work, the hardware guys only connected one port for simplicity. And I was the lucky guy that could implement the virtual MUX driver :slight_smile: