Abstract: A telecommunication system provides voice and data communications over a conventional telephone line that can be dynamically switched from voice mode to any of a plurality of data modes (e.g., fax, modem, or VoiceView protocols) during a single conversation. Each station includes a telephone for voice communications and switching means for selectively connecting the telephone to the telephone line in voice mode and disconnecting the telephone while operating in one of the data modes. A modem provides data communications over the telephone line in any of a plurality of data modes. Voice is the default mode of operation. Prior to switching into a data mode, the originating station first transmits a start signal over the telephone line that includes a mode signal indicating one of the data modes.

Abstract: A telephone interface system is inserted between the telephone handset and base to provide automatic switching between voice and data modes of communication. The interface includes a modem having a receive port coupled to the telephone base speaker lines and a transmit port switchably coupled to the base microphone lines, a switch for selectively coupling the telephone handset to the base, and a processor for monitoring data received by the modem and controlling the switch to automatically decouple the telephone handset from the base when data is being received or transmitted by the modem. The modem includes a tone generator that generates a predetermined start signal to signal a remote unit at the other end of the communication link to enter data mode prior to transmission of data. Similarly, the modem includes a tone detector to detect a start signal sent by the remote unit that causes the unit to switch into data mode in preparation for receiving data.