Tomorrow's Phone Calls

One day we all may find it useful to have a facility for sending documents, writing and pictures across the telephone lines. A detector at the sending end would quickly transmit the signals representing the document to a printer at the receiving end where the documents would be accurately and quickly reproduced.

View-phone would become an easy facility to provide; not that the findings in America indicate an overwhelming demand for us all to be seen as well as heard on the telephone.

Conference telephone facilities could become widely available and multi-channel cable television could also consume some of that capacity, but perhaps the greatest use, initially at least, will be in what our Post Office now calls Prestel.

The system will link the subscriber's television set to a public computer via his telephone. By dialling the appropriate number on the telephone and connecting the television receiver to the circuit, the user will have at his disposal sixty thousand or so pages of information, and all sorts of services which the telephone and the television on their own could never provide.

The television receiver is fitted with a small memory capable of storing the digital information necessary to generate one page of display. The conversion to Prestel also requires fitting the television with a key pad, rather like the finger panel of a pocket calculator.

On dialling the central computer the massive memory there transmits the signals to the small memory on the television set. These signals generate the first page of the instruction sequence. The picture welcomes you to Prestel and gives you any message it has stored for you in its memory. You, of course, can leave a message for someone else to pick up. Prestel talks to you in that strange computer fashion of asking you questions to which you can answer 'Yes', 'No', or give a number.

By asking questions the Prestel computer finds out what services you require, whether you want to find out the closing prices on the Stock Exchange, what is on at the theatre or something more complicated. Your answers on your key pad dictate when the memory in your set will receive a new set of instructions from central control and what those instructions will be.

Leaving a complicated message may prove difficult but as long as you are prepared to accept the alternatives Prestel offers, your wife can, for instance, learn whilst you are on your way, that you are arriving at the station at the time you have keyed in from your number pad, or that you are not coming home at all.

Then there are more subtle applications. On file in the main memory could be a whole host of valuable data ranging from, for instance, the Highway Code, to when you are likely to be approved for a mortgage. Because the computer can respond to your 'Yes', 'No' or number answers, it can actually give you advice.

One programme I tried was designed to help those anxious to adopt a child. The first question was, 'Are you applying on behalf of yourself only? If so key zero, if not key one.' I keyed zero, for the sake of argument, and up came question two. 'Are you the parent of the child?' Again zero for no. 'Are you over twenty-five?' I lied a little and said 'no' again and this proved too much for the computer. 'You are not eligible to adopt,' came back the answer.

If I had told the truth about being over twenty-five that would have made a difference and another question might have emerged before a final answer was given. Exactly the same technique is being used in some hospitals now for routine diagnosis of patients' complaints. The computers in this case are not public ones on an open network, but maybe the time will come when the Prestel computer will also tell you what is the matter with you, even if it takes a while longer for it actually to prescribe a treatment.

Prestel will also play games with you. Computerised noughts and crosses, mazes, and problems like balancing fuel consumption in the retro-rockets of your Mars lander against the gravitational pull of the planet so that you land at a comfortable speed without running out of fuel, are all in the compendium at computer headquarters.

In fact it is easy to forget that what Prestel is really trying to do is get you to use the phone, The Post Office does not want to engage in games or even take over completely from the Citizen's Advice Bureau, but it is in business to sell telephone calls, and the advent of Prestel gives it a mighty potent marketing weapon. But Prestel and all other new services which will emerge in its wake can only work if the capacity for these extra services is built into the system. It is optical fibre communication which promises to make that possible.

(From Tomorrow's World by M. Blackstad, BBC Publications)