What is voipextension - required for module Voip Script UI - web-based interface for developers to create and test VoIP Drupal scripts

I have installed VOIP Drupal and linked it to a Twilio account. Thanks for the detailed handbook. http://drupal.org/node/1078710

I set Pickup script to voip_weather_report and it does answer when a call is received (though it does not provide the weather report, think I need to install something for it to work).

I would like to try creating a script and within Site Building - Modules there is VoIP Drupal - Voip Script UI which is described as:

"Provides a web-based interface for developers to create and test VoIP Drupal scripts"

It states it depends on: Voipextension which is "missing"

Is this a yet to be created module?

I would like to try creating a script but do not know how to get it included in the list of scripts used to choose at "Pickup script name"