Build Your Own Rotary-Dial Cell Phone

hwestiii writes "Yet another indicator of how unrepresentative of the main Slashdot crowd I am (meaning 'old') is that, like vinyl records, 8-track tapes, and Pintos, I can remember when rotary dial phones were items of everyday use, and not some object of retro-cool pseudo-nostalgia. Imagine my delight, then at finding this project in which an old rotary phone is turned into a cell phone. To give credit where its due, I originally found it linked from Hack A Day. I know nothing about home-built electronics projects, but this is enough to make me want to learn. If this catches on, imagine what they'll have to do to those 'turn off your cell phone' messages that play in movie theatres."

Comments

What the hell kind of phone is THIS?

[IO ERROR]

What really makes me sad is the knowledge that many people today have never even seen a rotary phone, let alone used one.

If, however, on the off chance you find yourself stranded in South English, Iowa, where the only pay phone in town is still rotary, this is how it works.

Pick up the phone and wait for dialtone. Insert a dime. (Yes, this phone still costs a dime!) Now, see the holes arranged on the disc? Find the one corresponding to the digit you want to dial, insert your finger, and rotate the disc clockwise until you hit the stop. Remove your finger. Wait for the dial to rotate back to its original position. Repeat as needed.

While you were dialing, did you hear those clicks? The circuit is actually being interrupted at a rate of 10 times per second. (This will be 20 times in some other countries.) The switching equipment in the central office measures the number of clicks and the time in between them to determine the number you dialed.

For more information, I suggest reading old articles of Phrack.

Rotary Dialing - Reality

[wcdw]

10 times per what? Only if you're dialing a zero.

As any old phone phreaker knows, one can dial any (land) phone - even today - by clicking the receiver. To dial a three, for example, one clicks the receiver three times (within a second).

If you don't believe me, pick up your house phone and try it. This once was useful information, in the days of rotary phone locks, but now is just more useless trivia cluttering up my brain. ;)

Interesting facts about rotary and digital phones

[Audacious]

1. Rotary phones were built to last (unlike many digital phones). They can survive a drop from a two story building onto concrete. Just go down, pick it up, plug it in, and it will work.

2. Rotary phones can withstand 300lbs of pressure before they will break or deform.

3.Rotary phones can withstand temperatures of up to 1,000 degrees. This may seem a stretch, but rotary phones have been in buildings which have burnt to the ground and still worked.

4. You do not need to be able to dial a rotary or digital phone. You just need to be able to push the button/hanger on the phone. As the original poster stated, the way in which rotary phones work (not cell phones mind you) is that they disconnect for a short period of time (like a 1/10 of a second) and then reconnect. What you might NOT know is that all digital land lines can be operated as a rotary phone too. So in an emergency, all you need to do is to tap the button/hanger on your phone's base with a slight pause between the dialing of the numbers. It will still connect. (So to call 1-411 would be one click, a slight pause, four clicks, pause, one click, pause, and one click. Try it sometime.) (I used to do this to dial out from the university on phones with a phone lock on them! ;-) )

5. Digital phones sometimes have a switch on them to switch between rotary mode and digital mode. You can switch it to rotary mode, dial the number (and hear the antiquated clicks), and then switch back to digital mode to handle any of those "Press 1 to do Blah". I discovered this at my mom's house. She had rotary service (way out in the country!) but I'd dial the line, let the roatry part go through and then switch the phone over to digital mode to do things.

6. Digital phones can be dialed by whistling into them. It isn't easy but you can do it if you practice long enough (and are bored enough).

7. One of the last interesting things to know is that if you are ever, ever stranded somewhere with a broken phone and you need help, you can still use the phone line and dial the phone. All you need is to bare some of the wire and you have a telegraph. Hold the two wires together to complete the circuit and then use the two wires just like you would the button/hanger. Take them apart and you break the connection. Hold them together and you've got a connection. Operators are probably not as smart as they used to be about this (since telegraphs are not so common place anymore) but it used to be that you could do the old SOS and they would send someone. However, if you dial 911 using the above method and twist the two wires together afterwards the police will come out to investigate.

Just a bit of FYI stuff. :-)

A much simpler solution

[laing]

Motorola makes something called a "Cellular Connection". It's a box that plugs into the phone on one side, and provides an RJ-11 POTS (Plain Old Telephone Service) connection on the other. It supports pulse dialing too so there's no need for any PIC firmware debugging.

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Sigs are a waste of space