A new telecommunications product called Watson, made by Natural MicroSystems Corp., of Natick, Mass., promises to turn an IBM Personal Computer into a dramatically upgraded telephone answering machine and give the user several voice-messaging functions as well.

Watson consists of a plug-in circuit board and sftware that allows the IBM PC to store incoming and outgoing voice messages on a floppy or hard disk drive. Through the same technology found in compact disk players, Watson takes voice signals and turns them into the on/off digital code that a computer is able to understand and remember.

Unlike a standard answering machine that leaves only one message for all callers, Watson allows the user to create different messages for different people. These messages can also be directed to other callers, as long as everybody involved has an access code.

Natural MicroSystems president Charles Foskett developed Watson mainly for use by small businesses, since a full-function PBX and voice-mail system are usually cost-effective only for larger companies. The idea was to make Watson the conduit for messages that are often missed through telephone tag, in effect, giving smaller companies their own downscaled PBX system.

The $849 price tag includes such features as a built-in modem, an electronic appointment book, a clock, phone list, and communications software. Companies that plan on using Watson to store a large number of messages, however, will need a hard-disk version of an IBM PC or PC compatible, at an average additional cost of $3,000.