THE telephone network is the nervous system of our civilization, carrying messages of demand and direction, of pain and pleasure, to collective enterprises and to individuals alike. The telephone instrument itself is a mere end organ which enables any of us to make use of billions of dollars worth of complex switching and transmission equipment.
A new car is a new and complete means of transportation, but a new telephone instrument can be only a small alteration in a massive electronic organism that seems to change with glacial slowness. For this reason it is far easier to see what sort of advances in telephony are technologically possible than to say when they may actually take place, and I doubt if anyone can make firm and detailed predictions concerning the future.
Nevertheless, we are in a period of change. Phones now come in colors of choice other than black, and in several new shapes. New services are available. We should expect many new things in the future. What may they be?
Let us consider first the field of new services. A friend of mine told me recently that he would like to turn off his phone while he is working on a novel. I explained to him that just disconnecting the bell would lead to endlessly repeated but uncompleted calls for which the telephone company would pay. There would be complaints that his phone was out of order. To all of this he agreed, but he asked if he couldn’t just throw a switch and have something in the telephone office say, “This telephone is not out of order; the subscriber has voluntarily disconnected the ringing signal.”
The suggestion seemed a sensible one, but I had to tell him that it was impractical at present, at least in his area. The reason lies at the heart of the possibilities and difficulties of many new services that might be popular and valuable.
The automatic switching equipment in telephone central offices has the complexity and subtlety of a large-scale computer. However, much of the older equipment represents an early stage in the development of electronic organisms, and its powers of adaptation are small. Fundamentally, an automatic switching system performs two functions. It interprets the dial signal as a demand for a certain telephone connection, and it sets up the desired talking path. The first function, that of interpreting the dial signal, might be thought of as a mental function, and the other, that of establishing a talking path, as a muscular act.
In the first sort of automatic switching system, a sort still very economical for small installations, the brains are of a very limited and unadaptable type. Further, in this step-by-step kind of switching system, the brains are scattered all through the body, like the complicated ganglia of dinosaurs, which were sometimes larger than the lump of nervous tissue in the skull. One can teach a stepby-step switching system to do even one new thing only by the most drastic and expensive surgery.
Common-control systems, which first appeared in 1921, represent a tremendous evolutionary advance. In them, a “brain” carefully records the dial signal and then deliberates on what to do. When it has decided, it sets tip the talking path by using physically separate equipment. Modern common-control equipment can be taught to do many new sorts of things.
At present, the most advanced switching systems in use are composed primarily of electromechanical devices such as relays, though a few vacuum tubes and transistors have been grafted onto them. However, work is progressing on switching systems made up of tiny transistors, which operate thousands of times as fast as relays. Such an electronic switching system will have a quick, subtle, and adaptable brain which can be taught many new tricks.
The advent of electronic switching has opened our eyes to all sorts of new services which are technically possible, whether or not they ever come into actual use. Among these is certainly the phone-disconnect notice my friend wanted. Other possibilities include the ability to dial a selected group of telephone numbers by setting a pointer or by one or two pulls of the dial (by pushing one or two buttons, if push buttons replace dials); a centralized answering and recording service, in which there is no special equipment on the subscriber’s premises; ways of breaking into a busy connection in case of an emergency; and a host of other possibilities. Which among these will come into being and when they may be available, no one can tell, but electronic switching will make them easy. And some, at least, will be possible in areas now served by common-control electromechanical equipment, perhaps through the addition of electronic equipment.
We may expect not only better service; we may expect to be able to reach people more certainly. By using transistors, it has been possible to put a radio receiver as good as that used in mobile telephony into a case little larger than a king-size package of cigarettes, and which includes batteries for four days of continuous operation. If a person carries such a receiver about with him in an urban area, it is possible to signal him selectively by making his receiver, and only his, buzz when he is wanted on the telephone. He can then go to the nearest phone and call to see what the message is. Indeed, commercial radio-paging services are in operation in some cities, and the telephone companies are trying them out.
Does this presage or assure a two-way phone in your car or in your plane, if you have one, or perhaps even in your pocket? Technically, it makes such things very near. By using transistors, we can build a tiny receiver which can be on and ready to signal the owner twenty-four hours a day without a noticeable drain on a car’s batteries. Including a suitable transmitter, the whole car telephone could fit into the glove compartment or be incorporated with the radio. Further, pocket telephones are not technically absurd.
WILL next year’s car come equipped with a telephone as well as a radio? Not unless something changes. And that something has nothing to do with the technological limitations of radio, nor is it a matter within the control of the telephone companies.
Mobile telephony requires the use of radio waves which can penetrate the canyons of streets, and such that nondirectional antennas can be used for transmission and reception. Of the frequencies which are suitable, those which extend from perhaps 50 to 890 megacycles, the government has allocated roughly 50 per cent to ultra-high-frequency television, 7 per cent to ordinary television, 25 per cent for government use, 4 per cent for amateur radio, 4 per cent for FM, and only one third of one per cent for all mobile telephony. While the problem of the universal mobile telephone has its technical side, it also involves both the demand for such a service and the availability of enough suitable radio frequencies. The continued allocation of these frequencies to other uses could keep the telephone out of your car, plane, or pocket, however great our technical know-how may become.
There will still be telephones in your home and office, however, and these are bound to become better in a number of ways. Indeed, one aspiration which has been often expressed is to make the telephone so good that telephoning will be as satisfactory as meeting face to face.
Partly, what is called for is a better voice signal. A good telephone call is perfectly intelligible, but economy precludes its being hi-fi. However, for special uses, such as conference use, a higher quality of speech can be provided either by means of special circuits or by means of complicated terminal apparatus, which makes a more subtle use of the transmission capabilities of standard telephone circuits.
Of course, if we are to confer satisfactorily by telephone rather than dragging our weary bones repeatedly to Washington and elsewhere, we will have to transmit pictures as well as speech. Television transmission facilities are available, but they are at present too costly for anything but very important conferences or very large meetings. For some reason, they haven’t been used much for either.
I feel certain that someday pictures will be sent not only in connection with conferences but in connection with some telephone calls as well. A couple of years ago the Bell Laboratories experimented with a device called Picturephone, which sent a series of still pictures, one a second, over an ordinary telephone connection as an adjunct to telephony. However, the pictures proved too fuzzy to be of any real use. Perhaps a picture intermediate in quality between Picturephone and present-day television is called for.
To provide picture transmission to telephone users, new and more economical ways of sending electrical signals from point to point must be developed. Happily, great advances have been made in the electronic art of signal transmission. One of these is the transistor, which in amplifying a communication signal uses much less power than a vacuum tube. In fact, the power consumed by a transistor amplifier can be sent over the same wires used to carry the signal itself.
Along with the transistor has come a new way of sending signals over wires, called pulse code modulation. Ordinarily, we send a voice or picture signal as a smoothly but rapidly varying electric current which must be transmitted and amplified repeatedly with all its subtle intricacy undistorted. However, a way has been found of representing such signals as sequences or patterns of off-on pulses. Such pulses can be amplified simply and cheaply and reshaped repeatedly during transmission without any degradation in the ultimately reproduced voice or picture. Further, such signals can be sent great distances through pipes called waveguides. They can travel as electromagnetic radiation having a frequency perhaps 50 billion cycles of alterations per second through thousands of miles of a metal tube around two inches in diameter.
I believe that ultimately such transmission by means of off-on pulses will make television as an adjunct to the telephone economically possible, for some uses at any rate.
SUCH electrical pulses as I have mentioned above are the natural language of computers and business machines. These electronic brains have never used pen and paper, nor human speech. They write on and read from magnetic tape in a language consisting of sequences of pulses. One can speak to them or hear from them, control them or be controlled by them at a distance, by transmitting such pulses by wire or radio. Sometimes such machines translate their internal language of pulses into printed English characters, but this is merely for the benefit of their human associates.
We usually think of such machines as huge giants chattering away at a superhuman rate. Indeed, they do talk back and forth over communications channels, but the world of tomorrow will be full oi a host of electronic machines of all degrees of size and complexity. In fact, today’s teletypewriter is an early member of the race. Cash registers and like business devices often punch a record of their operations and conclusions into paper tape, which can be transmitted electrically from point to point. Future machines will almost certainly record on and be operated from magnetic tape. We can imagine a time when small machines in stores, insurance offices, and small business enterprises will store up a tape record of each day’s operations. Then a big machine at a bank, an accounting service, or a central office will call the little machines up during the night and record what happened during the day.
I like to think of a time when each secretary’s typewriter will produce a magnetic record as well as the usual typescript, a record which can be filed, reproduced, sorted over, or transmitted to some distant concern by quick electronic means. Indeed, an experimental device has already been built which will transmit text which has been recorded on a magnetic tape over a telephone circuit at a rate of about 800 words a minute. It is about the size of an office typewriter. I see communication between machine and machine and between man and machine as an important part of the business of the telephone companies in the not-distant future.
Beyond all this there are more distant and less concrete possibilities. The design, construction, and installation of the transatlantic telephone cable, in which 104 delicate and precise vacuumtube amplifiers function on the bottom of the ocean, beyond the reach of human adjustment or repair, was an engineering feat of a scope and difficulty comparable with that of establishing an artificial satellite. But in the future we may have manned as well as unmanned satellites, established in their orbits for scientific or military reasons. If manned satellites come to be, they will provide valuable radio relay sites for spanning the oceans with television as well as voice. Perhaps later on we will have to face the problem of communicating with men on the moon, or on Mars.
Calculations show that the electronic techniques used in the telephone system will do even this job. But when will men go to Mars? And will they perhaps go there to get away from the ubiquitous and insistent telephone?