Old Rotary Phone Gets Called Into Action

The more glass we punch with our fingertips, the more we miss fun physical interfaces like the rotary phone. Sure, they took forever to dial, and you did not want to be one of those kids stuck with one during the transition to DTMF, especially if you were trying to be the 9th caller to a radio station, but the solidly electromechanical experience of it all was just cool, okay? The sound and the heft made them seem so adult.

[Tal O] gets it. He’s all but finished bringing this old girl into the 21st century without giving anything away on her surface. Inside are some things you’d expect, like a SIM800 GSM module for the telephony part, and an ESP32 to count the pulses from the dialer and communicate between it and the GSM module. But it also has a few things we haven’t seen before. The entire journey is outlined in a five-part video series, and we’ve got part one dialed in for you after the break.

Although [Tal] got the ringer working to prove it could be done, he didn’t want to have a separate 12V circuit just to run the bells. Also, the bells and their electromagnets take up a lot of space, so he compromised with an mp3 of a rotary ringer. [Tal] also wanted a way to have dialed-number feedback without cutting up the phone to add a screen, so he found a text-to-speech library and made the phone speak each number aloud as soon as it’s dialed. It uses the same internal speaker as the ringer, but we think it would be neat if the feedback came through the handset speaker.

If [Tal] is looking for another modern convenience to add to this phone, how about speed dial?

19 thoughts on “Old Rotary Phone Gets Called Into Action

    1. Dial phones are as cool as a cucumber, i have two 1930s desk phones which work well. You need a dial gizmo, Google this item and an old phone will do lots of modern tricks, beware of crappy modern reproductions.

  1. I have one on our ADSL line. It’s original and unmolested – other than the rewire for BT plug.
    I manged to find one of those BT dtmf tone dailers to make calls, tho you also used to be able to get your phone to do DTMF for stored numbers.
    It’s still fun to “hit the hook” and remember the good old days of bypassing dial locks for free calls :)

    1. I’ve got one laying around waiting to be finished aswell. I’d love to use DECT for it, but since I can’t manage to find any DECT modules for actual telephony, i’ll probably have to resort to voip or something like that.

  2. I remember I used to “hack” the radio station call-ins for the “9th caller” by dialing the first 6 numbers of their phone number during their lead-up and when they would finally say “Call now”, I’d wait a couple seconds more then dial the last number. A couple times I actually got my call in and won. One time it was an artist’s entire album collection. Good times.

  3. What’s the reason to use an ESP32 – which is a WiFi SoC just to count pulses and control a GSM modem? That has not much more sense than the RasPi in a thermostat like vacuum controller, just because the guy who did it preferred to program in Python. Now his controller needs a Linux-Shutdown :-)

    1. thanks, i came for this comment.
      obviously the Pi would need a 16GB microSD card with a full blown linux installation (window manager, browser and maybe a mysql instance) and would essentially run python. through anaconda and inside a jupyter notebook.

      back in 2001 i made a pc based TV streamer using a BT878 TV capture card and a cisco wifi card to overcome the limitation of some missing coax cabling in the wall. the entire setup, including the kernel and the embedded filesystem was stored on a 8MB smart media card, it had ffserver and a tiny https daemon to give web based remote control for changing the channels – and booted into a ramdisk.
      nowadays one would look for a raspbian image of gazillion gigabytes… strange how things changed.

    2. The main 2 reasons for the esp32
      dac for the speech and wifi so I will able to do firmware update without the need to connect to the esp.
      The ota is already implemented and dialing 9 when the handset is on the hook gets it activated by running the esp as access point.

      Also – was in plan – to add a setting page (served as html) that will add functions like phone book with speed dial.

  4. I love it! I’ve been dreaming of getting a few old dial wall mounted phones. Oh well… only money. But I’ve also been on a binge to add tactile inputs and external displays (LEDs, NeoPixels, multi-seg LEDs, numitrons, …) to things. I’ve found bare ATmega238Ps, using their internal oscillator, a great way to be I/O multiplexers, input and output device controllers via I2C or SPI to my more involved PIs and next I’m looking at connecting them to my AMD desktop. It feels great to have broken free of the confines of my monitors and keyboard!

    1. I also have an original candlestick phone, but a slightly later one with a dial on the base. Usual plaited cord, bakelite junction box, etc. NOT a modern plastic imitation! I was a BT engineer for a good few years – I know about suchlike things! Had it on POTS. Used to have it wired to a modern cord, so it plugged into the house landline sockets and was a good conversation piece, especially as it was actually working and it would dial OK with the bell shunt wire also connected to stop other bells tinkling whilst dialing. Speech quality was a little “hollow”, for want of a better word! No bell for the candlestick itself but other phones rang, so no problem. Now just an ornament, sadly, as I no longer have a landline. Thought about doing other things with it but decided to keep it as original.

  5. I also built one of these recently. Specifically designed to have no features that the original didn’t have: you can make calls and you can receive calls, and that’s it. I also did my best to make it behave like the original: click-click sounds from the earpiece when you dial, a ‘ding’ when you put the receiver down etc. Only giveaway is that you don’t need to plug it into the wall. Gloriously pointless.

    It’s based on an Adafruit sim800 feather which is small and neat, with a cheap Chinese dc-dc to make ~25V and a motor drive chip to drive the bell.
    Now when my children whinge at me to buy them a mobile phone, I have the answer!


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