Mobile Telephones in the 1940s

Starting in 1946, with a pilot program in St. Louis, Missouri, AT&T launched its Mobile Telephone Service (MTS).  By 1948 the service was available in 100 cities and towns and along highway corridors.  The service ran on 25 VHF radio channels, using half-duplex FM; handsets on mobile installations had a push-to-talk button.  All calls were placed through human operators.  Here is a Bell System promotional film from the late 1940s about the wonders of mobile telephony and how it worked.

The separate tube-based transmitter and receiver weighed 36 kg together and were usually mounted in the trunk of automobiles, taking up a substantial part of the space.  The film notes that the installation “may require a larger battery and generator”.  The service was horrifically expensive.  In present-day (2020) dollars, the subscriber fee was around US$180 per month, and local calls cost between US$3.60 and US$4.80.  The service was never very popular, with no more than 5,000 subscribers placing around 30,000 calls a week.  The limited number of VHF channels would have precluded expanding much beyond that, anyway.

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Author: John Walker

Founder of Ratburger.org, Autodesk, Inc., and Marinchip Systems. Author of The Hacker's Diet. Creator of www.fourmilab.ch.

13 thoughts on “Mobile Telephones in the 1940s”

  1. Correct me if I’m wrong by cell phones still use radio channels. I saw one of those trunk installations I believe in the early sixties. The fellow who owned it had a bunch of coal strip mines in Western Pennsylvania. He caught a bunch of us swimming in a strip pond and used it to call the police. We were let go with a warning. I think it was because the girls were topless.

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  2. PhCheese:
    He caught a bunch of us swimming in a strip pond and used it to call the police. We were let go with a warning. I think it was because the girls were topless.

    Well, it was a strip pond, so it hardly surprising the girls were topless.

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  3. PhCheese:
    He caught a bunch of us swimming in a strip pond and used it to call the police. We were let go with a warning. I think it was because the girls were topless.

    You got my attention. 😎

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  4. No self respecting police officer with a Rolls Royce and an Asian chauffeur would be without a mobile phone. (I couldn’t find a scene with it but …)

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  5. PhCheese:
    Correct me if I’m wrong by cell phones still use radio channels.

    Yes, the connection is still via radio, but the technology is entirely different.  The original mobile phones had a total of 12 or 24 channels (depending on the installation), and each channel carried only one conversation at a time.  That meant that a big city with a 24 channel installation could support only 24 subscriber conversations at a time.  If you wanted to make a call to or from the vehicle, you had to wait for a free channel.  (Of course, the same thing would happen making long distance calls on land lines at peak periods—sometimes you’d have to wait half an hour for a free trunk line to the destination.  It’s just that the number of trunk lines was many times that of the mobile channels.)

    Modern cellular technology such as 4G LTE uses a host of signal processing black magic and digital wizardry to squeeze thousands of virtual channels out of a much larger number of physical channels in the UHF or microwave bands.  Sending voice as packets means numerous conversations can share the same channel at the same time.  Further, since cells are smaller, the same frequencies can be reused at many locations within a city.  The advanced transmission modes and smaller cells dramatically reduces the power requirement in the mobile device, which makes it practical to operate from a self-contained battery (which has much higher energy density than anything from the 1940s).

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  6. Then, there’s perhaps the most famous mobile phone in 1960s television.

    When I first got a mobile phone in the 1990s, I called it a “shoe phone” for years.

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  7. Ha Ha. Obviously that strip thing worked on the girls. The problem was that the water was high in acid and when you got out it looked like you had a tan. You had to sneak into the house and wash so your parents didn’t know you were in the strip pond. Wish I had some pictures especially of one girl in particular. Funny what an old man can still remember. We called the area of all the strip mines the dark side of the moon. The guy that had the phone had logged the land, then stripped the coal, then later filled the holes with garbage and sold the land to the airport authority. He retained the mineral rights and his heirs a fracking for gas in the shale deposit. Obviously he did well.

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  8. 10 Cents:

    G.D.:

    10 Cents:
    No self respecting police officer with a Rolls Royce and an Asian chauffeur would be without a mobile phone. (I couldn’t find a scene with it but …)

     

    I could.

     

    More Info Here.

    I don’t see video, Gerry.  Thank you for finding a still.

    No video 10 Cents, sorry, but the still was the best I could do. I thought that qualified as a “scene”.

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