Although things have been relatively slow here on the forum for the past year or so, we have been actively implementing new systems based on VoIP Drupal.
In fact, we are now currently in the process of designing VoIP Drupal 2.0 and figuring out what it might take to port the framework to Drupal 8. Although the VoIP Drupal API has been quite stable for the past 5 years, we have learned many things along the way and decided that it was time to take VoIP Drupal to the next level.
If you are interested in contributing ideas and/or code to this effort, please let us know.
Looking forward to collaborating with you!
Leo (and the Terravoz team)