1-we are trying to write an application which dial a number and play a voice file instead of microphone input. Is it possible in Maemo (N900)?
we can not find any ""Answering Machine " like program in N900. is this means that there is no way to play a voice file instead of Microphone input?
There is a way. Play that voice file and make pulseaudio believe it's a proper input, and disable the microphone input. For more information see my question:
How to redirect from Audio Output to Mic Input using PulseAudio?
It is possible but you need a good pulseaudio knowledge to do it, I can already set it easily on my PC using pavucontrol. Drop me a message (or better, answer my question) if you bite the bullet and decide to learn how to use pactl/pacmd.