A growing number of telephony applications primarily developed for the Phone Operation Center is now freely available on sourceforce: poc-apps.sf.net. As of now you can download the maze (english+german), spoken human rights (german) and a small time announcement application from the SVN repository. The maze has been solved to the very end only about twice since its first appearance in 2005 at the annual Chaos Communication Congress (22C3). Moreover the in-game phrase "Du stehst vor einer Wand." ("You're facing a wall.") is well known as it has been cited numerous times at the 22C3 and similar gatherings.
The code so far is written in Tcl as Asterisk AGI, however there is no need to know either Tcl or AGI in order to use the application. More about Asterisk may be found in the Conceptual Introduction to Asterisk.