I’ve recently become obsessed with VoiceXML, a markup language that manages voice interactions between humans and computers. It is endless amounts of fun. Voxeo offers a hosted dev environment that provides developers with a VoiceXML interpreter and an endless supply of free phone numbers to use with your applications. Here’s an app that took 30 seconds to create: (415) 830-3015. Call it right now, I dare you.
Combining VoiceXML with any dynamic language makes voice applications easier to build than traditional HTML-based apps. There’s no need to worry about visual design or common security vulnerabilities (unless someone finds a way to execute an SQL injection over the phone, in which case they deserve an award). Here’s an app that took an afternoon to create: (415) 992-6871. It uses PHP to query FatSecret’s API and generate VoiceXML that provides callers the nutrition facts of any food they want. Well, not any food. I haven’t bothered to expand the grammar past a few hundred food items so it can only query common foods but the logic is all there.
The ease of experimenting with a non-visual environment feels quite liberating and I have a couple other apps in the pipeline. Hopefully I’ll finish the first next week.
It’s worth noting there are newer, easier-to-use APIs that emulate VoiceXML environments and cater to the Web 2.0 crowd. The two most popular are Twilio and Tropo. They stand on the shoulders of W3C’s work and offer simple methods of integrating voice and SMS services into existing systems. Both are definitely worth checking out if you plan on experimenting in the realm of voice applications.