Concerns About Using the Telephone with Personal Computers

Source: Jef Raskin, "Concerns About Using the Telephone with Personal Computers" (9 October 1979)-- in "The Macintosh Project: Selected Papers from Jef Raskin (First Macintosh Designer), Circa 1979," document 12, version 1.
Location: M1007, Apple Computer Inc. Papers, Series 3, Box 10, Folder 1.

The ordinary telephone lines are the only bi-directional electronic communication links between most people. This is not only true for the United States of America, but for a significant portion of the rest of the world as well. The telephone lines are therefore the most obvious and accessible means for implementing inter-computer communications at low cost.

The technical problems have been solved, and electronic interfaces between computers, terminals, data acqusition and display devices and the phone line are inexpensive, often costing as little as a few months telephone service. Nothing special is required of the telephone service in order to use these devices: the telephone system does not distinguish voice from digital signals encoded as sequences of tones (or combinations of tones). In fact, it uses certain tones itself to establish connections, and even to do some bookkeeping.

The bandwidth of the telephone service imposes some limit on the speed of transmission. Inexpensive interfaces operate at a maximum of 30 characters received or transmitted per second. More expensive interfaces could run at, say, four times this rate over the same lines. Such faster interfaces for personal use are still a few years away.

The main technical difficulties in using the phone network for personal computer communications is in adopting protocols that will allow computers to speak to one another. This problem is being addressed by a number of groups such as the PCNET, to name one among many. Assuming that this problem can be solved to a point where such communication becomes commonplace, or if the current time sharing and data base services proliferate to the point where individuals begin to use them as individuals (instead of using them exclusively in connection with their employment or studies), we find another potential problem. The telephone system might start to move to disallow such use.

At first it is not clear why the telephone system might oppose personal computer communications. It would seem that it would only mean increased use, and thus increased revenue. Dr. Gammill, of the Rand Corporation (in his Position Paper on Personal Computers in the 1980's) and others have suggested that the telephone company might seek to limit or control computer useage in order to maximize income by charging a higher rate for computer transmissions. Dr. Gammill points out that "from the point of view of the phone companies, personal voice communication is under-charged due to regulation of that market", and since the tarriffs only apply to voice communication, new tarriffs, at (presumably) higher rates would be applied to digital communication. This would require that the phone company have special equipment that can distinguish between the two grades of service.

I would like to suggest that there is a technological reason that the telephone companies might be concerned with digital use of a system intended for human communication. The phone system is based on a statistical model of phone use. There are not enough lines and interconnections so that all possible non-conflicting calls can be made at once. The amount of equipment actually installed is based on assuming a certain percentage of the possible calls are being made at any time, and that calls have a certain distribution of lengths. Some calls last just a few seconds: "Hi, Jean?" "Hello Mary." "I'll be over in five minutes." "See you then, bye." "Bye." Others last longer.

The amount of equipment and personnel the telephone company needs depends on the maximum acceptable number of calls that cannot be completed due to lack of equipment, the total number of calls, and some statistics on the length of those calls. The problem with allowing digital transmission probably has little to do with the increased number of calls due to such use. In the next few years the number of personal computers in use will remain under ten million, with only a percentage of these being equipped for phone transmission. But there are over 100 million phones in daily use. So the number of calls made for the sake of a computer connection will remain insignificant for the time being. The same cannot be said for the length of those calls.

As a very simple example, assume that there are 30 calls per hour (at random times) on a system that can handle one call at a time. Also assume that the system requires no time at all to reject a call when the line is busy. If each call lasts one minute, then the probability that a given call was placed without waiting is about one half (it depends on some other factors such as the delay between retries). As these calls double in length, the probability that a given call was placed without waiting gets extremely small. If the calls are longer than two minutes in this example, they won't all fit--some calls can never be made. Notice that the number of calls has stayed the same.

I suspect that this phenomenon is one of the things the telephone companies are concerned about. It is not the number of calls, but the large increase in average length that may well cause problems.

What must not happen is that the users of personal computers get into a cat and mouse game with the phone companies. A possible senario is this: a phone company sets up a special, higher rate for computer use. They add a circuit that detects the usual modem (the modem is the device that attaches a computer or terminal to a telephone line) frequencies and charges accordingly. At the same time they apply to the FCC to make those frequencies mandatory (ostensibly to help promulgate standardization and the free interchange of data). The computer manufacturers make a modem that "sounds" to the phone company more like the voice, so their detectors don't work. The phone company builds a better detector, and begins to throw in random .15 second pauses that interfere little with speech but play hob with digital transmission. The computer buffs respond with error-correcting codes that correct for small pauses, and make still more voice-like modulation. The phone company could respond with a rate scheme that vastly increases the cost per minute after 10 minutes... This could be an expensive and counter-productive war.

If we have the various utitilty commissions and the Federal Communications Commission involved it may be years before true personal computer networking gets under way. There are various strategies that may be applied now: attempts to have legislation passed that will not allow the telephone company to discriminate based on the content of a telephone call (if they start with computers, will they eventually get the right to charge differently for, say calls with good news and calls with bad news? Do they have the right to listen in on a call at all to determine its content?) One might argue that deaf people can communicate via terminals over the phone and that they should not have to suffer a higher rate.

There might be an attempt to get the telephone company to give a policy decision on the matter--although this could possibly help accelerate their coming down on what we might see as the "wrong" side. Apple Computer is, rather naturally, interested in this situation, and would like to hear from interested parties

Document created on 6 June 2000;