Asterisk is a Free (as in GPL) IP PBX written in C and running on Linux and OpenBSD. Asterisk offers an laguage neutral API that allows controling the dial plan, call flows and creating complex integtrated IVR and similar systems. 

Asterisk::AGI is a Perl module which make the task of implementing AGI using programs in Perl easy and fun (if you consider writing Perl scripts fun, of course ;-)

The lecture will feature a brief descrition of Asterisk, a  walk through of AGI and Asterisk::AGI features and a demonstration of a naive movie ticket ordering system which will be built during the lecture in front of the audiance.

URLs:

Asterisk: http://www.asterisk.org
Asterisk::AGI: http://asterisk.gnuinter.net
Me: http://codefidence.com