AT&T; Introduces Digital Phone Service to Japan, U.K.

AT&T; on Monday demonstrated a digital telephone service to Japan and Great Britain based on an international standard, making it easier for companies to set up worldwide communications networks.

The service can be dialed up like a regular phone call once a special digital line is installed to the customer. It is expected to be available to many other nations by the end of the year, American Telephone & Telegraph Co. said.

Unlike conventional analog phone lines, digital lines enable the transmission of computer data and video conferences. They also provide distortion-free phone calls and far faster fax transmissions overseas.

AT&T; began offering dial-up digital lines to other nations in 1988, but these lines are based on a North American standard, which transmits data at 56 kilobits per second. Meanwhile, most of the rest of the world uses digital lines that transmit data at 64 kilobits per second.

A kilobit is 1,000 bits. A bit is the smallest piece of information used by a computer, and represents either the digit 1 or 0.

The difference in standards has meant that U.S. customers must use an adapter to send computer-based information abroad, which creates the possibility that errors can be introduced into the data during transmission, said AT&T; spokesman Rick Wallerstein.

With the new service, which was announced last month, a U.S. company could set up a phone and data-transmission network around the world based on the 64-kilobit standard.

Before the dial-up digital services were available, the only way for a company to send computer data overseas was through a leased, private line. These “dedicated” lines are more expensive in general than dial-up services, which bill customers per minute of use like conventional phone lines.

The new Switched Digital International service was approved Feb. 5 by the Federal Communications Commission.

The service in Japan is provided in cooperation with Nippon Telegraph and Telephone Corp. and Overseas Communications Japan, while the British service is a venture with British Telecom PLC.

At a news conference, AT&T; demonstrated a video conference hookup with Tokyo using two of the new phone lines simultaneously. Because video transmissions contain a huge amount of data, their quality is improved by sending it over two lines at once.

But the picture quality still is lower than that provided by normal television broadcasts. The image is grainy and the motion is delayed, giving the impression that the video is being shown in slow motion.

The equipment used for the video conference is made by PictureTel Corp., which has a marketing agreement with AT&T.;

AT&T; also demonstrated a personal computer linkup through the phone lines. When changes were made on a computer screen in New York, they could be seen on a similar computer screen in Tokyo by watching the TV monitor used for the video conference.

In addition, AT&T; demonstrated a digital telephone, which provides far better voice transmission quality than conventional phones, and an optical scanner that allows the user to scan documents or objects electronically, then send them over the phone lines abroad, where they appear on a computer screen.

Nippon Telegraph & Telephone also demonstrated computer and video hookups over the new phone lines.