said by Takamurasan :Do you have any suggestion for a PDF or a website where I can look more deeply into this? I started looking, I think it might just be what I'm looking for.
A quick overview (from the shell/terminal): [edited for grammar]
asterisk -rx "core show application EAGI"
Overview of AGI - EAGI is a variant:
http://ofps.oreilly.com/titles/9780596517342/AGI.html
Sample perl script:
http://www.voip-info.org/wiki/view/Perl+EAGI
Another option to get the audio stream:
http://jackaudio.org/
Have fun! :)