VoiceView works by switching the telephone line between voice and data communication modes. Voice and data communications occur in the same way they do today, but both share the same call. Voice communications and data communications each use the full bandwidth of the telephone line to deliver information during operation of the respective mode.
Voice mode is the default mode of operation. When in this mode, VoiceView-enabled equipment transparently behaves as normal telephone equipment. However, the equipment monitors the communications connection and the data connection for specific events and changes its mode appropriately in response.
When one person wants to send data to the other person on a call, the sending modem temporarily mutes the handset and sends a signal directing the other modem to switch to data mode. When the receiving modem receives the signal, it mutes its handset and prepares to receive data. After transferring the data, both modems unmute their handsets and normal conversation continues.
VoiceView supports switching into a special data mode that is optimized for quickly sending data and returning to voice mode. Using this special data mode, 2K of error-corrected data can transfer with only a three-second interruption in the conversation.
VoiceView-enabled equipment also includes a capabilities query that determines if equipment at the far end of a connection is VoiceView-enabled, and if so, what capabilities the equipment has. This feature allows VoiceView equipment to adapt to, and to optimize communications for, each connection.