Twilio, Tropo - who else for SMS and Voice apps?

Question

I've found Twilio and Tropo so far as services to aid SMS and Voice apps.

Are there others?

I am interested mostly in real-time speech recognition (i.e. the user can speak things and the system can respond based on that).

Also, if anyone knows what the speech recognition quality is like, it'd help!

Answer 1

For reliable SMS delivery we tested Tropo and Twilio and Twilio won hands down... Better API imo (including callbacks that make things like knowing how long a call lasted trivially easy), they manage the sending rate so you don't have to (Tropo discards SMS messages if you send too fast).

On the other hand, Tropo has speech recognition that works very well (although not as well on real-world cell calls in less than silent environments) and has integrated Twitter support.

Both offer excellent support. Tropo is free for development, but Twilio is so inexpensive that's probably a non issue.

My more detailed writeup is at http://pardner.com/2011/04/tropo-not-ready-for-prime-time-went-with-twilio/

(Since the blog was written I've learned Tropo fixed Twitter support, so that's actually a very cool feature in favor of Tropo. Turns out you can mix n match, our app uses BOTH.)

Answer 2

For speech recognition and an API-based telephony service, Tropo's about the only option. If you drop the speech reco requirement CloudVox (hosted asterisk apps) could be a possibility. Or you could install Asterisk yourself and use something like Adhearsion to develop your apps.

If you want to expand your scope beyond cloud telephony APIs, then you could take a look at VoiceXML, a W3C standard for building telephony apps. VoiceXML hosts generally support speech recognition. A search for "VoiceXML Hosting" will turn up several thousand options.

In the interest of disclosure, I'm one of the guys behind Tropo and we're a product from Voxeo, the largest VoiceXML host.