Andy Reinhardt
The promoters of two incompatible technologies that let document-conferencing applications send voice and data signals over the same analog phone line have avoided a potential standards skirmish by agreeing to work together for interoperability. Eliminating a battle between AT&T's VoiceSpan and Radish Communications Systems' VoiceView should help grow the market for voice-and-data modems for analog phone lines.
VoiceSpan, or SVD (Simultaneous Voice/Data), allows a new kind of modem that modulates voice and data onto a single carrier, letting you converse on the phone while exchanging data files. Because it uses unusual techniques for merging digitized voice and data, VoiceSpan doesn't work with some digital-phone switches and interactive-voice response systems. Voi
ceView's technique involves switching between voice and data signals. With VoiceView, speech is transmitted with maximum analog fidelity, and data moves along at a 9600-bps clip. But conversation ceases when you're sending a file or waiting for a screen update.
VoiceView is economical because you can add it to existing modems with a firmware upgrade, whereas VoiceSpan entails sophisticated new modulation techniques. VoiceView supporters like Intel, Hayes, and Microsoft say that the low cost of licensing Radish's multiplexing technique will make it a cinch to add to some existing products.
Now AT&T has licensed the Radish VoiceView technology for incorporation into its VoiceSpan modems. This means that a VoiceView switching modem will be able to talk to a VoiceSpan modem (which will revert to a switching mode). VoiceView modems still won't support simultaneous voice and data communications.
VoiceSpan's and VoiceView's window of opportunity is framed by how quickly digital telephony service
s like ISDN are deployed in the U.S. ``Radish is not a perfect technology for us because we're assuming people have a constant line for voice,'' says Gary Gysin, vice president of marketing for document-conferencing supplier Crosswise. AT&T's SVD, he says, is ``a better approach for document conferencing.'' Despite their appeal today, Gysin contends, both AT&T's and Radish's techniques are merely ``stopgaps until ISDN.''
Voice/Data Technologies to Coexist
