The Cutting Edge: COMPUTING / TECHNOLOGY / INNOVATION : Voice and Data Together

People at home or in small offices who use their computers to send and receive information via the telephone generally have to put up with a major inconvenience: The phone line can be used for the PC, or for voice communications, but it cannot be used for both at once.

Telephone companies have been working for years to develop a solution to this problem. In effect, the technology, called ISDN, converts a single phone line to a multiple line, but it has been slow to catch on, and remains expensive.

A small Colorado company, Radish Communications Systems, has come up with a more modest but far more practical solution to the problem. The technology, known as VoiceView, has been licensed by many modem manufacturers and will be widely available this year.

HOW IT WORKS:

1. The PC user calls the receiver on the telephone.

2. The caller and the receiver turn on their personal computers. As soon as the modems are turned on, they start listening in on phone line.

3. The caller drags the icon of a file he or she wants to send to the VoiceView icon. This movement generates a tone heard by a switch inside the modem.

4. This tone causes the switch to change from voice communications to data transmission.

5. After this transition, the modem sends the document through the phone line to the other PC while placing the phone conversation on hold.

6. The document pops up on the receiving PC after a brief delay, and the phone line switches from data back to voice transmission.

Sources: AT&T;, Radish Communications Systems Inc. Researched by JENNIFER OLDHAM / Los Angeles Times