Co-founder here: We are an active team at Startup Weekend Columbia. We pitch tomorrow afternoon here's more about our company:
http://blog.killthelandline.com/post/32529411766/about-us
We are using Tropo with Heroku for the MVP.
http://blog.killthelandline.com/post/32529411766/about-us
We are using Tropo with Heroku for the MVP.
http://plivo.com/pricing/ (Disclaimer: I was in the same YC batch as Plivo. I do really like the service compared to Twilio or Tropo.)
More seriously, I'm familiar with the Tropo API and know that no matter what direction this product goes, Tropo is a capable platform to build it on.