Error Messages

A Web site author typically uses message boxes to notify users of a graphical Web browser that an error has occurred. Under the WTE, message boxes are not rendered to the caller, yet the call might be blocked (for more information, see Message Box Management). For this reason, an application must not use message boxes when running under the WTE. Instead, use wave files or TTS to communicate error messages to the caller.

Internet Information Services (IIS) servers and proxy servers maintain a default error page that they return when they cannot fulfill a client's request. For example, IIS and proxy servers return the default error page when a Web browser tries to navigate to a page or server that does not exist.

An administrator should ensure that the default error pages are authored so that the WTE can render them, possibly by adding the VOICEFILE attribute to appropriate HTML elements. That way, if the caller selects a key that has a broken link, the engine will play a friendly error message. For example, "We are sorry, the page you want is currently unavailable. Please call again later." Because Internet connections can fail, it is especially important to have friendly default error pages on a proxy server offering access to applications through the Internet.