Making a voice call


I have a Fastrack Xtend connected to a Windows PC, and would like to automatically make voice calls and trasmit pre-recorded audio.
If possible i’d program the PC only and use the modem as a passive serial device (no OpenAT).
I can make a voice call with “ATD number ;” but once the call is established i don’t know how to transmit audio from the PC (.wav or whatever) to the call…



You will have to create an OpenAT appliaction for this purpose. You can have a look at PCM record play sample which is provided with Sierra Wireless Software Suite .The sample is used to record an audio stream and then paly it on the speaker or voice call.
You can change the sample as per your requirement i.e. you can change the .wav file to hex format and store it in a buffer and play it using the sample on voice call.


Then you would have to provide a separate audio connection from the PC’s soundcard output to the XTend’s mic input.

SiWi do not support audio over the serial interface (you would have to write an App to do that…)


OK. Do you think i could directly connect the analog audio output of the PC to the microphone input of the FXT?
As i read in the manual, microphones should be connected to pins 4 & 5 of the serial port, so i’d have to do both serial and analog communication thru that port, right? With some sort of cable that splits in two…


I think you’d at least need some attenuation…?

It is probably more helpful to think of the serial port as separate from the audio lines - they just happen to share the same connector…

See above - same connector, but different ports.


But what are you actually trying to achieve here?
If you explain your goal, people might be able to suggest more appropriate ways to get there…