As promised, the Disposable Phone Numbers™ project is now available as open source via Sourceforge.
To answer some other questions that have been asked: The equipment you need to run DPN is actually quite minimal. The demo box you reach when you call the demo telephone number (+1 312 967 6568) is a nice Wiindows XP machine, but nothing truly extraordinary. The Voxeo “Prophecy” server requires Windows XP (for now; Linux is coming “soon”) and if you use pre-recorded announcements instead of text-to-speech, you don’t really need much in the way of horsepower.
The demo box itself isn’t connected to the telephone network directly. The telephone number is supplied by Voxeo (again, as a freebie to developers) and the demo box uses SIP to accept the incoming call. I don’t bother routing the call to an actual telephone handset, so this demo box doesn’t even have an ATA.
In other words: if you’ve got a desktop machine with some spare disk space, you can set it up as a speech recognition/text-to-speech/web server/PHP/servlet/SIP server and run the DPN demo without any additional equipment.
Voxeo, BeVocal, and some other companies also have free developer accounts; you can run your application on their hosts, and connect to them via Free World Dialup or the regular phone network.