make a phone call with hsdpa dongle and play audio and record user feedback in c#

Question

I have done all call dialing part and it works. Now I need to play audio and record the responce audio comming from the other end.I just need to know how can I pass the audio to the dongle and send it through the call, and how to record the feedback that is comming from the other end

this is my working cord for dialing phone number(I'm using huwavi E173 hsdpa Dongle)

        `SerialPort port = new SerialPort();
        port.Open();
        string t = port.ReadExisting();
        Thread.Sleep(100);

        string cmd = "ATD";
        string phoneNumber = "071********";
        port.WriteLine(cmd + phoneNumber + ";\r");


        port.Close();`

Answer 1

You could try to issue an 'AT+FCLASS=?' command. If the modem responds back with a string containing '8', then you can use the VOICE mode commands (VTX/VRX/VTR) perhaps. If it doesn't... which I expect from most GSM modems, then you're out of luck.

There might be a proprietary way to do it, but it might not be exposed through the serial port of the modem (pushing audio data through the serial line is very inefficient, so most modem chipsets would have a separate set of I2S / other interface pins for the audio).