What sorts of voice applications are best suited for VoiceXML? Here are a few ideas.

Information retrieval (IR) is a good match for VoiceXML. In an IR application, audio output tends to be pre-recorded information. Voice input can be highly constrained (e.g., a few browsing commands and limited data entry), or it can be quite rich (e.g., arbitrary street addresses). A good example of an IR application is one where the user first designs a personal voice newsletter at a web site, and then calls in periodically to browser through the newsletter. The newsletter may contain news, sports, traffic, weather, and stock information, as well as more specialized information such as intranet-based company news. This service can be funded by subscription, advertisement, or connect time.

Directory assistance applications work well in VoiceXML. AT&T’s has a new VoiceXML toll-free directory assistance service, powered by TellMe, which you can try out in the United States by calling 800.555.1212. It is so incredibly effective that the automation rate climbed from 8% to 55%, saving AT&T $20 million a year. Remarkably, customer satisfaction has risen by over a third along with this increased automation.

Electronic commerce is another area. Customer service applications such as package tracking, account status, and support are well suited to VoiceXML. Financial applications like banking, stock quotes, and portfolio management are another good match. Catalog applications have to be done right, because voice conveys much less information than graphics. Catalog applications work if the customer is looking at a printed catalog (e.g., clothing), or knows the exact product already (e.g., a book, CD, or DVD title).

Telephone services like personal voice dialing, one-number “find-me” services, voice mail management, and teleconferencing can easily be voice-enabled through VoiceXML. Personal voice applications attached to individual phone lines can be very important sources of revenue.

Because standard Web security features apply to the voice web, intranet applications can also be written in VoiceXML for inventory control, ordering supplies, providing human resource services, and for corporate portals.

Unified messaging applications can leverage voice. E-mail messages can be read over the phone, outgoing e-mail can be recorded (and in the future transcribed) over the phone, and voice-oriented address information can be synchronized with personal organizers and e-mail systems. Pager messages can be originated from the phone, or routed to the phone.

There are many other areas where voice services can be used, such as checking the status of bids at an electronic auction site, authorizing bill payments, scheduling pickups of charitable donations, ordering a wake up call at a hotel. Doubtless there are many services not yet conceived of.