Rotary Cell Phone Prototype

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12 Responses:

  1. Ben says:

    I'm bothered that it makes DTMF tones when dialed. Why simulate a pulse to tone converter?

    • Thomas Lord says:

      Bonus points if you can also dial by flashing the red button.

      • robert_ says:

        Does the US telephone network still accept pulse dialing?

        • Thomas Lord says:

          I just checked by trying to dial another number of my own. Yes, the network still accepts it. No, I'm no longer adept at it.

          • Chris Davies says:

            Is that really true? I remember here in the last exchanges that could handle pulse dialing were removed in the 90s. My grandparents still had a pulse dialing phone right up until they were forced to upgrade.

            I can't imagine there's anyone in the world who manufactures an all-digital telephone exchange hardware who have pulse dialing support for shits and giggles. Presumably you must have a decades old electromechanical exchange or something.

            • Thomas Lord says:

              Is that really true?

              Honest and for true.

              I can't imagine there's anyone in the world who manufactures an all-digital telephone exchange hardware who have pulse dialing support for shits and giggles.

              Apparently you can even get a libre software PBX (Asterisk) that supports pulse dialing. I can't imagine why you'd think it's a big deal, though I can believe some telco exchanges get screwed.

              I live in Berkeley and I very much doubt that we still have an electro-mechanical exchange.

              Nevertheless, please enjoy this decades old article about the Berkeley phone system, "Rapping on Tapping", published in June of 1968 in the Berkeley Barb.

              The article is by "Military Editor" Lee Felsenstein who I understand to be the same Lee Felsentein who helped start Osborne and who implemented the best yet known form of social networking.

              "Rapping on Tapping"

              Community Memory

              • jwz says:

                When I was like 8, my mom had a friend who worked at The Phone Company (when it was still The Phone Company) and I got to see the exchange. It was this enormous clacking room full of relays and it was the coolest thing in the world. At least, I think it was enormous, I mean, I was 8. Anyway, the next year I got to see it again and it had been replaced by a single computer half the size of a refrigerator that made no noises at all. Even back then I found that both pretty cool and pretty disappointing.

            • MattF says:

              Many years ago, a (former) colleague of mine told me that when he worked for the phone company they had a guy who listened to the way the relays in the exchange clicked and could diagnose problems from the way they sounded.

            • thielges says:

              Sometimes supporting backwards compatibility is more effective than phasing obsolete stuff out. There might be some old piece of hardware out there (a fire alarm system for example) that dials out with rotary pulses. You don't want an actual fire to inform you of the BC dependency.

            • I'll chime in with another data point of pulse dialing working, at least around these parts. (I've heard reports from people situated in other locations that pulse dialing no longer works for them. Some of them have fiber-to-the-home and telephone service provided by the ONT.) My one rotary dial phone still works as does a phone in a clock radio that has an actual keypad, but only knows to dial in pulse mode. Everything here is still 100% copper.

              It's quite amusing to hear a telephone modem drive its hookswitch relay in rapid fire fashion for pulse mode dialing. Which makes me curious as to how well the relay would stand up to such use -- I doubt the manufacturers consider it.

              Up until a few years ago, I had some neighbors whose landline phone service was pulse only. Touch tones were simply ignored and the dial tone kept on going.

    • Nick L says:

      Mobile phones mostly speak something related to ISDN so there are neither pulses nor DTMF tones when dialing, it's just an affectation - the entire number is sent to the network once you hit Go. On the other hand, once you're connected the far end may well use DTMF so having tones might be "better" assuming it knows how to actually transmit them ?

      But honestly maybe he just likes DTMF better. Fair play he built it and other people just talked about it.