A teleconferencing system for voice and data provides interconnections among user sites via a central station. User stations at user sites each alternate operation between a data mode connecting a user computer and modem to a user telephone communication path and a voice mode connecting a telephony circuit to the communication path. The teleconferencing system is adapted for conducting a voice conference over standard telephone lines while allowing simultaneous viewing of data objects such as slides, graphs, or text. A host computer connected to the central station serves as a central repository for storage and retrieval of data objects for use in teleconferences.