Thanks for the info. Looks like I should re-evaluate things as at the time Tropo seemed to be a coming-soon/developer-only service that didn't have details around production pricing nailed down. The Prophecy IVR info scared me into thinking that Tropo might have similar limitations.
You said you inquired about Voxeo/Tropo but the pricing you mention above has absolutely nothing to do with Tropo.
Tropo is 100% free for development use - always.
Production Tropo pricing starts at 3 cents per minute with free second-leg (connected) calls, free voice recognition, free high-quality speech synthesis, free 24x7 support, no minimum, and no port limitations.
http://tropo.com
Prophecy IVR is a completely different service. It's intended for a different customer set, and those customers love the product.