A NEW system demonstrated in Washington this month offers Internet business users a simultaneous phone link.

Until now, companies using the Web to sell to consumers have been hampered by the lack of sales assistants in cyberspace to answer shoppers queries. On some Web sites, you can leave your phone number with a request for the company to call you back, but if you are surfing the Net, that usually means your phone line is already tied up. By the time the call reaches you, it may be too late.

The new system, developed jointly by electronics giant Rockwell and Web phone company Netspeak, permits someone browsing a Web site to introduce a live phone call over the Internet to a company representative. The representative can see the page the caller is looking at and display live video images on the customer's computer screen.

Internet calls do not match the quality of standard phone lines, but the system's designers believe that being able to make contact on the spot will be more important.