Mobile Telephone History

One party talked at a time with Mobile Telephone Service or MTS. You pushed a handset button to talk, then released the button to listen. (This eliminated echo problems which took years to solve before natural, full duplex communications were possible.) Mobile telephone service was not simplex operation as many writers describe, but half duplex operation. Simplex uses only one frequency to both transmit and receive. In MTS the base station frequency and mobile frequency were offset by five kHz. Privacy is one reason to do this; eavesdroppers could hear only one side of a conversation. Like a citizen's band radio, a caller searched manually for an unused frequency before placing a call. But since there were so few channels this wasn't much of a problem. This does point out greatest problem for conventional radio-telephony: too few channels.

Art imitating life below. This cartoon is from the April, 1948 issue of The Bell Laboratories Record. It reads, "Hello, Mr. Bunting. I've changed my mind -- I'll take that accident policy!"

Shortly after this cartoon appeared the July 1948 BLR reported that a taxi cab driver with a mobile phone reported a stuck car on a railroad crossing, thus saving the broken down car and its motorist from disaster. Possibly the first radio-telephone rescue of its kind. This incident happened at a "grade crossing of the Nickel Plate Railroad at Dunkirk, New York." Dr. Scott Savett has found a photograph on the web of a representative Dunkirk rail crossing. The Dr. says, "According to a source on the Web, there were about five grade crossings in Dunkirk, so there's no guarantee that the one shown above is actually the one where the call was made." Still, this photo gives you an idea of the country. I wonder if the county history museum knows of the crossing's place in mobile telephone history.

Cellular telephone systems first discussed

The MTS system presaged many cellular developments. In December,1947 Bell Laboratories' D.H. Ring articulated the cellular concept for mobile telephony in an internal memorandum, authored by Ring with crucial assistance from W.R. Young. Mr. Young later recalled that all the elements were known then: a network of small geographical areas called cells, a low powered transmitter in each, the cell traffic controlled by a central switch, frequencies reused by different cells and so on. Young states that from 1947 Bell teams "had faith that the means for administering and connecting to many small cells would evolve by the time they were needed." [Young]The authors at SRI International, in their voluminous history of cell phones[SR1], put those early days like this:

"The earliest written description of the cellular concept appeared in a 1947 Bell Labs Technical Memorandum authored by D. H. Ring. [but see previous page, the key difference is that Ring describes true mobile telephone service, ed.] The TM detailed the concept of frequency reuse in small cells, which remained one of the key elements of cellular design from then on. The memorandum also dealt with the critical issue of handoff, stating "If more than one primary band is used, means must be provided for switching the car receiver and transmitter to the various bands." Ring does not speculate how this might be accomplished, and, in fact, his focus was on how frequencies might be best conserved in various theoretical system designs."

Here we come to an important point, one that illustrates the controlling difference between conventional mobile telephony and cellular. Note how the authors describe handoffs, a process that Mobile Telephone Service already used. The problem wasn't so much about conducting a handoff from one zone to another, but dealing with handoffs in a cellular system, one in which frequencies were used over and over again. In a cellular system you need to transfer the call from zone to zone as the mobile travels, and you need to switch the frequency it is placed on, since frequencies differ from cell to cell. See the difference? Frequency re-use is the critical and unique element of cellular, not handoffs, since conventional radio telephone systems used them as well. [Discussion] Let's get back to Young's comments, when he says that Bell teams had faith that cellular would evolve by the time it was needed.

Important conventional mobile telephone handoff patents are: Communication System with Carrier Strength Control, Henry Magunski, assignor to Motorola, Inc. U.S. 2,734,131 (1956) and Automatic Radio Telephone Switching System, R.A. Channey, assignor to Bell Telephone Laboratories, Inc. U.S. 3,355,556(1967)

While recognizing the Laboratories' prescience, more mobile telephones were always needed. Waiting lists developed in every city where mobile telephone service was introduced. By 1976 only 545 customers in New York City had Bell System mobiles, with 3,700 customers on the waiting list. Around the country 44,000 Bell subscribers had AT&T mobiles but 20,000 people sat on five to ten year waiting lists. [Gibson] Despite this incredible demand it took cellular 37 years to go commercial from the mobile phone's introduction. But the FCC's regulatory foot dragging slowed cellular as well. Until the 1980s they never made enough channels available; as late as 1978 the Bell System, the Independents, and the non-wireline carriers divided just 54 channels nationwide. [O'Brien] That compares to the 666 channels the first AMPS systems needed to work. Let's back up.

In mobile telephony a channel is a pair of frequencies. One frequency to transmit on and one to receive. It makes up a circuit or a complete communication path. Sounds simple enough to accommodate. Yet the radio spectrum is extremely crowded. In the late 1940s little space existed at the lower frequencies most equipment used. Inefficient radios contributed to the crowding, using a 60 kHz wide bandwidth to send an signal that can now be done with 10kHz or less. But what could you do with just six channels, no matter what the technology? With conventional mobile telephone service you had users by the scores vying for an open frequency. You had, in effect, a wireless party line, with perhaps forty subscribers fighting to place calls on each channel. Most mobile telephone systems couldn't accommodate more than 250 people. There were other problems.

Radio waves at lower frequencies travel great distances, sometimes hundreds of miles when they skip across the atmosphere. High powered transmitters gave mobiles a wide operating range but added to the dilemma. Telephone companies couldn't reuse their precious few channels in nearby cities, lest they interfere with their own systems. They needed at least seventy five miles between systems before they could use them again. While better frequency reuse techniques might have helped, something doubtful with the technology of the times, the FCC held the key to opening more channels for wireless.

In 1947 AT&T began operating a "highway service", a radio-telephone offering that provided service between New York and Boston. It operated in the 35 to 44MHz band and caused interference from to time with other distant services. Even AT&T thought the system unsuccessful. Tom Kneitel, K2AES, writing in his Tune In Telephone Calls, 3d edition, CRB Books (1996) recalls the times: "Service in those early days was very basic, the mobile subscriber was assigned to use one specific channel, and calls from mobile units were made by raising the operator by voice and saying aloud the number being called. Mobile units were assigned distinctive telephone numers based upon the coded channel designator upon which they were permitted to operate. A unit assigned to operate on Channel 'ZL' (33.66 Mhz base station) might be ZL-2-2849. The mobile number YJ-3-5771 was a unit assigned to work with a Channel YJ (152.63 Mhz) base station. All conversations meant pusing the button to talk, releasing it to listen."

Also in 1947 the Bell System asked the FCC for more frequencies. The FCC allocated a few more channels in 1949, but gave half to other companies wanting to sell mobile telephone service. Berresford says "these radio common carriers or RCCs, were the first FCC-created competition for the Bell System" He elaborates on the radio common carriers, a group of market driven businessmen who pushed mobile telephony in the early years further and faster than the Bell System:

"The telephone companies and the RCCs evolved differently in the early mobile telephone business. The telephone companies were primarily interested in providing ordinary, 'basic' telephone service to the masses and, therefore, gave scant attention to mobile services throughout the 1950s and 1960s. The RCCs were generally small entrepreneurs that were involved in several related businesses-- telephone answering services, private radio systems for taxicab and delivery companies, maritime and air-to-ground services, and 'beeper' paging services. As a class, the RCCs were more sales-oriented than the telephone companies and won many more customers; a few became rich in the paging business. The RCCs were also highly independent of each other; aside from sales, their specialty was litigation, often tying telephone companies (and each other) up in regulatory proceedings for years." [Berresford]

Some claim the Swedish Telecommunications Administration's S. Lauhren designed the world's first automatic mobile telephone system, with a Stockholm trial starting in 1951. [SE External link] I've found no literature to support this. Anders Lindeberg of the Swedish Museum of Science and Technology points out the text at the link I provide above is "a summary from an article in the yearbook 'Daedalus' (1991) for the Swedish Museum of Science and Technology http://www.tekmu.se/." He goes on to say, "The Swedish original article is much more extensive than the summary" and that "The Mobile Phone Book" by John Meurling and Richard Jeans, ISBN 0-9524031-02 published by Communications Week International, London in 1994 does briefly describe the "MTL" from 1951. But, again, nothing contradicts my contention that Richmond Telephone was first with automatic dialing.

On July 1, 1948 the Bell System unveiled the transistor, a joint invention of Bell Laboratories scientists William Shockley, John Bardeen, and Walter Brattain. It would revolutionize every aspect of the telephone industry and all of communications. One engineer remarked, "Asking us to predict what transistors will do is like asking the man who first put wheels on an ox cart to foresee the automobile, the wristwatch, or the high speed generator." Sensitive, bulky, high current drawing radios with tubes would be replaced over the next ten to fifteen years with rugged, miniature, low drain units. For the late 1940s and most of the 1950s, however, most radios would still rely on tubes, as the photograph below illustrates, a typical radio-telephone of the time.

As proof of their competitiveness, the RCCs serviced 80,000 mobile units by 1978, twice as many as Bell. This growth built on a strong start, the introduction of automatic dialing in 1948.

The first automatic radiotelephone service

On March 1, 1948 the first fully automatic radiotelephone service began operating in Richmond, Indiana, eliminating the operator to place most calls. [McDonald] The Richmond Radiotelephone Company bested the Bell System by 16 years. AT&T didn't provide automated dialing for most mobiles until 1964, lagging behind automatic switching for wireless as they had done with landline telephony. (As an aside, the Bell System did not retire their last cord switchboard until 1978.) Most systems, though, RCCs included, still operated manually until the 1960s.

Some claim the Swedish Telecommunications Administration's S. Lauhren designed the world's first automatic mobile telephone system, with a Stockholm trial starting in 1951. [SE] I've found no literature to support this. Anders Lindeberg of the Swedish Museum of Science and Technology points out the text at the link I provide above is "a summary from an article in the yearbook 'Daedalus' (1991) for the Swedish Museum of Science and Technology http://www.tekmu.se/." He goes on to say, "The Swedish original article is much more extensive than the summary" and that "The Mobile Phone Book" by John Meurling and Richard Jeans, ISBN 0-9524031-02 published by Communications Week International, London in 1994 does briefly describe the "MTL" from 1951. But, again, nothing contradicts my contention that Richmond Telephone was first with automatic dialing.

On July 1, 1948 the Bell System unveiled the transistor, a joint invention of Bell Laboratories scientists William Shockley, John Bardeen, and Walter Brattain. It would revolutionize every aspect of the telephone industry and all of communications. One engineer remarked, "Asking us to predict what transistors will do is like asking the man who first put wheels on an ox cart to foresee the automobile, the wristwatch, or the high speed generator." Sensitive, bulky, high current drawing radios with tubes would be replaced over the next ten to fifteen years with rugged, miniature, low drain units. For the late 1940s and most of the 1950s, however, most radios would still rely on tubes, as the photograph below illustrates, a typical radio-telephone of the time.

Let's go to Sweden to read about a typical radio-telephone unit, something similar to American installations:

"It was in the mid-1950's that the first phone-equipped cars took to the road. This was in Stockholm - home of Ericsson's corporate headquarters - and the first users were a doctor-on-call and a bank-on-wheels. The apparatus consisted of receiver, transmitter and logic unit mounted in the boot of the car, with the dial and handset fixed to a board hanging over the back of the front seat. It was like driving around with a complete telephone station in the car. With all the functions of an ordinary telephone, the telephone was powered by the car battery. Rumour has it that the equipment devoured so much power that you were only able to make two calls - the second one to ask the garage to send a breakdown truck to tow away you, your car and your flat battery. . . These first carphones were just too heavy and cumbersome - and too expensive to use - for more than a handful of subscribers. It was not until the mid-1960's that new equipment using transistors were brought onto the market.Weighing a lot less and drawing not nearly so much power, mobile phones now left plenty of room in the boot - but you still needed a car to be able to move them around."

In 1953 the Bell System's Kenneth Bullington wrote an article entitled, "Frequency Economy in Mobile Radio Bands." [Bullington] It appeared in the widely read Bell System Technical Journal. For perhaps the first time in a publicly distributed paper, the 21 page article hinted at, although obliquely, cellular radio principles.

Time Out From Texas Instruments:

"In 1954, Texas Instruments was the first company to start commercial production of silicon transistors instead of using germanium. Silicon raised the power output while lowering operating temperatures, enabling the miniaturization of electronics. The first commercial transistor radio was also produced in 1954 - powered by TI silicon transistors."

In 1956 AT&T and the United States Justice Department settled, for a while, another anti-monopoly suit. AT&T agreed not to expand their business beyond telephones and transmitting information. Bell Laboratories and Western Electric would not enter such fields as computers and business machines. The Bell System in return was left intact with a reprieve from monopoly scrutiny for a few years. This affected wireless as well. Bell and WECO previously supplied radio equipment and systems to private and public concerns. No longer. Western Electric Company stopped making radio-telephone sets. Outside contractors using Bell System specs would make AT&T's next generation of radio-telephone equipment. Companies like Motorola, Secode, and ITT-Kellog, now CORTELCO. Also in 1956 the Bell System began providing manual radio-telephone service at 450 MHz, a new frequency band assigned to relieve overcrowding. AT&T did not automate this service until 1969.

In this same year Motorola produces its first commerical transistorized product: an automobile radio. "It is smaller and more durable than previous models, and demands less power from a car battery. An all-transistor auto radio, [it] is considered the most reliable in the industry." [Motorola]

In 1958 the innovative Richmond Radiotelephone Company improved their automatic dialing system. They added new features to it, including direct mobile to mobile communications. [McDonald2] Other independent telephone companies and the Radio Common Carriers made similar advances to mobile-telephony throughout the 1950s and 1960s. If this subject interests you, The Independent Radio Engineer Transactions on Vehicle Communications, later renamed the IEEE Transactions on Vehicle Communications, is the publication to read during these years.