Zork Returns! Thanks to Open Source Asterisk PBX

TORONTO — A voice PBX system is typically thought of as
being all work and no play. How much fun can you have with a
system that is designed to provide voicemail and call extensions, right?

Turns out that when you open up the code and let developers run wild,
strange things can happen.

Such is the case with the open source Asterisk
PBX, which has at least a few strange implementations that developers
explained in a session at the IT360 conference here. The session was
officially called “Exploring Your Phone System,” but Asterisk developer
Simon Ditner called it “Crazy Things You Can Do With Your
Phone System.”

The crazy thing Ditner wanted to do was play Zork over the

Zork is a text-based adventure game that debuted in the late 1970s.
It became a popular series in the early 1980s with versions for the IBM
PC, Apple II and Commodore 64 systems. Ditner tried to take
that game and make it playable over the phone using only your voice.

His effort is called Zoip (a hybrid of Zork VoIP). In order to
build his phone-based game system, Ditner started with a stock Asterisk
installation and then added a number of items to do speech recognition
and text to speech.

In the game, the Zoip system reads out a Zork description using the Festival text-to-speech engine. For instance: “This is a small room with passages to the east & south. Bloodstains & deep scratches mar the walls.”

The user would then say either “east” or “south” to move to the
next area. In order to do the speech-recognition part, Ditner used the Spinx2
open source speech-recognition technology.

To glue the Asterisk, Festival, Sphinx2 and Zork text all together, Ditner
used Perl. He said it only took him 48 hours to get the project done, thanks to the openness of Asterisk and the community that surrounds it.

“Asterisk is three things,” Ditner said. “It’s an IVR , a PBX
and a media gateway.”

Ditner explained that at first he began his project as an approach to
implementing an Asterisk interface. “Gradually it became less about Asterisk and more about my application and the limit of my imagination,” Ditner said. “Asterisk can step out of your
way and let you do what you want.”

The same can’t be said of traditional commercial PBXs, such as those from
Nortel or Avaya. Ditner said his effort and other such
experimental efforts just aren’t easily possible by hobbyist developers like

But there is one pesky little limitation of Ditner’s Zoip application: copyrights.
Though no one has developed Zork in over two
decades, the original publisher, Infocom, still holds the copyrights. As such, Zoip is just a hobby project for nonprofit use.

Zoip isn’t the only “crazy” thing that was covered in the session. Asterisk developer Clod Patry followed Ditner with a
brief description of his voice-change-on-the-fly application for Asterisk.

He said some commercial entities have already used the voice-changing feature. In particular he noted that an adult toy
company came to him explaining that their female call center people didn’t
sound sexy enough. With Patry’s voice changer installed on Asterisk, they’ve
attempted to solve their problem.

Other implementations noted by Ditner on a somewhat lighter note is an
interactive voice game that could be played while on hold. If callers
score points, they move up the call queue; if they lose points then they end
up on hold even longer.

“You can do all sorts of crazy things with Asterisk that don’t make any
sense but are definitely entertaining,” Ditner said.

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