Tokyo — In a small apartment in a suburb of Tokyo, housewife Mariko Yamada selects her weekly menu from a catalogue on her monitor -- chicken fillet, ham, instant noodles, dried fish. She presses the code buttons to order them from a neighboring supermarket. In another house in the same Musashino district, 10-year-old Jiro is exchanging notes for his algebra homework with a classmate across town on a digital ``sketch phone,'' which sends handwritten documents and graphs on telephone monitors.
At a local bank, four executives sit around a table talking to their colleagues on the other side of town through the teleconference system.
These are part of a model plan of what the Japanese public telephone company, Nippon Telegraph and Telephone Corporation (NTT), is now testing. It foreshadows a society in the not-too-distant future, according to NTT, which has long held a monopoly on the telecommunications business in Japan.
The program, called Information Network System, or INS, is expected to furnish new telecommunications network and services in Japan in the next decade.
The components of network system are not in themselves new; what is original about NTT's plan, company officials claim, is the idea of linking the entire telecommunications network to one trunk line. In other words, telephone, facsimile, data, and image communication signals will be merged into a single digital network and then linked across Japan on one optical-fiber cable.
About the width of human hair, optical fibers are thinner and lighter than copper cables, but can carry several hundred times more volume of data. What's more, they provide clearer transmission because they are not affected by electrical disturbances.
Thus, under the new program, various communication services can be interlinked, and transmission and calls will be quicker and in the long run more economical, NTT claims. An official estimates that the program would lower the cost of a phone call by 30 percent.
This ambitious project comes at a time when the telecommunication industry is undergoing major changes. NTT, with 61 million telephones and annual revenue of about $19 billion, is now the world's largest telephone company after the breakup of American Telephone and Telegraph Company last year.
On Dec. 20, the Japanese parliament passed a law allowing private companies to enter the telecommunications business beginning April 1. To secure its position in the face of new competition, NTT already is developing what it considers to be the more profitable part of its business: providing a network of inter-city telephone links that can be used for various types of data communications and new telecommunication services.
NTT's INS program, which is being tested in two Tokyo suburbs until March 1987, is still too costly to be commercially viable immediately. But the future promises a service that could be applicable in various fields.
A telephone line linked to a facsimile can transmit messages simultaneously to several destinations -- at two seconds per page. Another for color prints sends a page in six seconds.
The sketch phone could be an ideal communications vehicle for the deaf, says NTT. If the person you call is out, you can leave hard-copy messages at the other end.
Probably more useful for the average consumer are the Captain and VAN (value added network) systems. Through a terminal at home, one can reserve airline tickets and make hotel bookings as well as buy everyday purchases from local stores.
The video teleconference system will allow businesspeople to hold meetings with colleagues in other cities. Hospitals could benefit from the reflection-circuit service with which they can monitor patients, even from a distance. And a message-communication service acts as a sort of message board for subscribers.
The model system had 148 subscribers last year, and expects to have 550 by the early part of 1985. By 1987 the digital communication service will be expanded to other major cities and by 1995, the network is expected to cover the entire country, NTT officials say.