It's a beautiful extension of their existing APIs and really does get you to ask the question, "Why do I need a separate phone device to communicate with others?"
I didn't have a killer idea or business idea to build on top of this so I decided to do something simple but make it available to anyone to use and extend. I built a browser-based phone that anyone can download and deploy to Google App Engine themselves. All you need is a Twilio account.
The phone has four features. Once you've logged into the application, you can do the following...
- Call anyone using a dial pad right in the browser
- Receive calls in the browser when people call your Twilio number
- Receive calls from friends that login to the app in their browsers
- Record voicemail if you aren't logged in to answer (and send you an SMS to let you know)
It was super fun to build and even more fun to use. If you'd like to get your own you can find the project on github - http://github.com/gtracy/phonefree-twilio. It's intended to be a turn-key solution for App Engine. Just deploy and go.
There are lots of opportunities to extend this if you're interested. I'd like to implement voicemail and SMS. I'd like to put a design on this so it looks nice. :) I'd also like to try implementing conferencing so you could have party lines right inside the browser. What else?