The VUI is an important element of a voice portal. A voice portal enables wireless and wireline subscribers to access information, check voice-mail and e-mail messages, and place calls over the telephone using nothing but their voices. Speech-based user interfaces such as those found in voice portals must be easy for users to control. Speech-recognition interfaces must also meet complex and important requirements, including understanding the basic laws of communication, eliminating the need for training, and responding appropriately to requests. By implementing a conversational VUI, network service providers can expect greater acceptance of voice-based products and services because users can naturally and immediately use them.

Voice portals are a logical extension of Web portals. Simply defined, to reiterate, a voice portal allows users access to information, check voice-mail and e-mail messages, and place calls over the telephone using nothing but their voices. The objective of a voice portal is to simplify the way people use telephones to communicate, access information, and conduct business.

Voice portals use powerful computers and software to recognize speech commands, find information, listen to audio streams, convert text into an audible format, and help users to keep in touch. A voice portal may be best thought of as a voice version of a Web browser that accepts spoken commands and returns audio data and responses. The potential breadth of commands, applications, and information that can be accessed with a voice portal is limitless. For example, a voice portal can add custom applications, such as a voice equivalent of a contact management program. In addition, voice portals can be integrated into existing telephone networks and aid in the basic user functions of that phone system, such as placing calls and handling voice-mail. Today, voice portals can read e-mail, manage your voice-mail, provide directions, read the latest news and sports scores, play a game, manage your schedule, and much more. In the future, voice portals will book your flights, arrange flower deliveries to your loved ones, and serve as your personal concierge.