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The insinuation of telecommunications into the daily fabric of our lives has been arguably the most important and surprising development of the last 25 years. Before this revolution, telephone service and its place in our lives had been largely stable for more than a generation. The growth was lateral, as the global reach of telecommunications extended, and more people got a telephone service. The distinction between oversea and domestic calls blurred with the advances in switching and transmission, undersea cable, and communication satellites. Traffic on the network remained overwhelmingly voice, largely in analog format with the facsimile (Fax) beginning to make inroads. A relatively small amount of data traffic was carried by modems operating at rates up to 9600 bits per second over voice connections. Multiplexing of signals was rudimentary—most connections were point-to-point business applications.

The contrast with today’s network is overwhelming. The conversion from analog to digital has long since been completed. A wide range of services, each with its unique set of traffic characteristics and performance requirements, are available. At the core of the change is the Internet, which is becoming accepted to handle all telecommunications traffic and functions.

In order to effect such a far-reaching change, many streams converged. At the most basic level was the explosive growth of the technology. The digital switching and processing that are intrinsic to the modern network are possible only through integrated-circuit technology. There is a number of examples of this technology at work. For one who has worked in data communications, the most striking is the voice-band modem. At the beginning of the era, the rule of thumb for cost was a dollar per bit per second. Modems were typically the size of a VCR. Integrated-circuit technology and other factors, which we consider next, contributed to the several-fold increase in performance, with 56 kilobits per second now routine with a modem costing pennies.


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