Copyright © Karl Dahlke, 2023
In the 1880's, just a couple years after the phone was invented, telephone service began in cities and towns around the world. A central office served a few dozen customers, but each office was an isolated hub of connectivity. Within 20 years, these islands would be interconnected by trunks, facilitating the "long distance" call. In 1892, telephone service began from New York to Chicago, across a distance of 950 miles.
At the outset, a human operator connected each call. When a caller picked up the phone, that action completed a circuit and notified the operator. She came on the line and said, “Number please.” The caller recited a 2 or 3 digit number, for the party he wanted to call. She placed patch cords into jacks in the vertical panel in front of her, thus physically connecting the two parties together. Once that call was established, the operator was free to place more patch cords into other jacks, as directed by the next caller. When the first call was complete she removed those cords, thus disconnecting the call. That was her work day.
As the telephone grew in popularity, it was not practical to have a human operator connect each call. Automation was well underway by 1890, for local calls and even long distance calls. Automation always displaces workers, while reducing costs for the customer. It is an inevitable consequence of capitalism, and it applies to every sector of the economy. We have a duty to assist our displaced workers, but we cannot stand in the way of progress. There are 13.5 billion cell phone calls made each day world-wide. If an operator completes a call in one minute, and works an 8 hour day, with an average of three operators needed to connect each call, we would have to employ 100 million operators to handle the load. This is obviously not practical. And there are other factors, technical factors, that make this scheme impossible.
That said, operators were still needed in certain situations well into the 1970's, and they still have a role to play today. I remember calling the operator for information, or placing a collect call, or verifying the status of a line that had been busy for several hours. Recall the words of Jim Croce, in 1972, “Operator, oh could you help me place this call.” Interactions with the operator were satirized by Lily Tomlin in her recurring skit, Ernestine The Telephone Operator, on Laugh In. I grew up watching Laugh In, and I always looked forward to Lily Tomlin. Her comedic timing was perfect.
The rotary dial phone ☎ was the standard for more than half a century. It facilitated calls, local and long distance, without the aid of an operator. In other words, it was the key to automation.
When the receiver 📞 rests on the cradle, "on hook" as they call it, it depresses two buttons, which interrupt the circuit. The buttons are down, the circuit is broken, and there is no call. The receiver contains a bag of lead shot, to make it heavier, so that it holds the buttons down. Yes, I took a phone apart and verified the presence of the lead weight. Without it, the receiver is light plastic, and feels insubstantial in my hand.
To initiate a call, the caller lifts the receiver off the cradle, i.e. "off hook". The buttons lift, the circuit is complete, the central office knows that your phone is active, and it sends dial tone to tell you, “Go ahead and dial.” From here, the dialling mechanism is simple in concept.
If the first digit in the phone number is a 6, place your finger in the 6 hole in the dial, and turn it clockwise until your finger reaches a stop bar. This action winds up a spring inside the telephone. Pull your finger out of the hole and release the dial, and the spring pulls it back to its start position. A governor ensures the dial turns at a constant speed. As it turns, a series of contacts, affixed to the dial, complete and interrupt the circuit. It literally hangs up the phone approximately eight times per second. If you dialled a 6, the dial interrupts the circuit 6 times as it winds back to its original position. If you dial a 7, that turns the dial a little farther, and as it winds back, there is one more click, one more interruption of the circuit. A machine at the central office counts the clicks, and infers the digit you just dialled. Once it collects the entire phone number, it makes the connection for you, with no human operator.
Once I understood the underlying mechanism, I had to experiment. I lifted the receiver "off-hook", the first step in making a call. Instead of dialling as usual, I placed the receiver on the desk. I would need both hands, and quite a bit of dexterity, for the next step. You don't have to be Buddy Rich to do this, but you do have to be fast and precise.
The receiver was on the desk, the buttons were raised, and dial tone could be heard in the earpiece. Using alternating hands, I punched the buttons down and up as fast as I could, 6 times, to dial a 6. In other words, I hung up the phone 6 times in rapid succession. I then waited half a second, as though I was turning the rotary dial for the next digit. In reality I didn't touch the dial at all. I then punched the next digit using the buttons, perhaps a 7. Wait, punch, wait, punch. After the last digit I lifted the receiver to my ear. The phone rang, and my friend answered.
“Hey,” I said, “you'll never guess how I called you.”
There were dozens of times I wasn't fast enough, or miscounted, and had to hang up and start over. More than once I punched in the wrong number without realizing it, and had to apologize to a stranger. No, I didn't try to explain what I was doing, I simply said, “Sorry, wrong number.” Finally I was successful, and I got better with practice. I had proved the concept. The dial telephone worked just the way I thought it did.
My mind wandered into a daydream, which was viable for several decades, until modern technology displaced the traditional land line.
I'm locked in a closet in a cabin in the woods. The cabin is owned by a madman, who will probably kill me in the near future. I'm not tied up, and I could probably break out of the closet, but he's right outside the door, and he has guns and knives, and the nearest neighbor is 200 yards away. The closet is unfinished, and I notice several wires running along the floor. One of them is the phone line. I flex the wires back and forth, back and forth, until they break from metal fatigue. A nail on the floor is sharp enough to cut through the insulation. (Phone wires are not protected the way electric lines are. They don't have the voltage, or the power.) At this point the line is cut in two. I hold the business end in my hand, and let the other end, the end connected to the telephone, float free. The nail neatly strips off the insulation, exposing two copper wires called tip and ring. They are bent outward so they don't touch, except for the tips which I can bring together. In one smooth motion, I put the tips together, and that completes the circuit. This is the same as lifting the receiver off the cradle. In half a second the central office sends dial tone down the wires. I do not hear it, because I don't have a telephone. I have to trust that dial tone is there, and the central office is waiting for me to dial.
I pull the tips apart and put them back together in rapid succession, click click click, 9 times, then leave them together. I have just dialled 9. A pause is needed here, just a half a second. Timing is everything in this game. I pull the tips apart and snap them back together, thus dialling a 1. After a second I do the same thing, thus dialling another 1. I have called 911. The dispatcher answers the phone, but nobody is there. There isn't even any background noise, just silence. Confused, she sends the police to investigate. They enter the cabin, I scream for help, and they rescue me. So ends my fantasy - an idea so original you haven't even seen it on tv.
This is almost impossible today. The murderer probably has a cell phone, and the cabin doesn't have a landline at all. If it does, it probably runs through the cable, which also provides tv and internet. I can't do anything meaningful with coax cable, with just my bare hands.
There was a variant of this idea however. On the tv show 9-1-1, episode Breaking Point, a woman stabs her husband and stuffs his body into a wall in her bedroom, rather like A Cask of a Montillado. He is not dead however, and fiddles with the wires to set off the burglar alarm. The police come, find him in the wall, and rescue him.
Signalling by clicks is slow and error-prone. In 1963, the Bell System invented the touchtone telephone. This phone presents a keypad, rather than a rotary dial. This keypad has 123 at the top, unlike the standard keypapds of the day, on cash registers and keybpunch machines, which had 789 at the top. Personally I prefer the telephone keypad; I think it is more intuitive. However, I must remain flexible, because the computer that I am using right now, to type this article, has 789 at the top of its numeric keypad. I have, within one meter of my right hand, both keypad layouts.
The dialling mechanism is simple in concept, but there are some important considerations. The engineers had to be well versed in music, and harmonics, as we shall see below.
The phone basically sings to the central office. Oscillators had become cheap and reliable, so press a 6, and your phone sends a tone to the central office indicating a 6. Band pass filters listen for certain tones, and recognize the digits dialled.
Sounds simple - but what if your sister is singing in the background, as you are dialling the phone. Could those notes be falsely interpreted as digits? To get around this, each button sends out two tones, two different notes. The system is called dual tone multi frequency, or DTMF. Your sister can't sing two notes at once, so we're ok.
The implementation is simple. Each button makes contact with a wire in its row, and in its column. Each row has an oscillator that produces a tone, and each column has an oscillator that produces a tone. Therefore, 6 generates the tones associated with the second row and the third column. These are the dual tones for the digit 6. In a phone from the 70's, you could separate these tones by holding down multiple buttons at once. Hold down the 6 and the 9 for instance, and here the pure tone that is associated with the third column. Hold down the 6 and the 5 for the second row. I haven't had a phone like this in my hand for 30 years however, so you probably can't perform this experiment at home.
There is another problem, which the engineers of the 60's recognized. What if your sister is playing the radio in the background, while you are dialling the phone? A song plays many notes at the same time. What if two of those notes together happen to dial the digit 6? To guard against this, the tones are deliberately non-harmonic. The tones for 6 would never be C and G, for instance, because that is a natural interval, a fifth in music. G is the fifth note in the C major scale. Instead, pairs of notes are just a bit off. They would never occur in music, unless the singer was terribly off key. The engineers must have done a good job, because I have tone-dialled a phone with loud music playing in the background, and the call went through.
When DTMF became available, the phone company charged extra to use the service. Not a lot, a few bucks a month, but still, it was ridiculous! It is cheaper for the phone company if everyone uses DTMF. You can place a call in just a couple seconds by pushing buttons; whereas rotary dialling can take eight seconds or more. They should have offered the service for free, or even offered a discount for those who wanted to use it. Instead, they charged extra. Within a couple months the invisible hand moved. Radio Shack sold phones with a keypad and a switch on the side. When the switch was down, the buttons simulated a rotary dial. Press 6, and the phone sent 6 clicks to the central office, as though you had dialled. You could hear the clicks in the earpiece. After the call was placed, you might want to flip the switch back up, to send tones, because some companies started to listen to these tones to process credit card numbers, to pay bills or make purchases. Customers had the convenience of push button dialling, and the phone company received no revenue for it, while wasting extra circuit time to connect the calls. Within a few years they abandoned their ridiculous pricing scheme, and allowed everyone to use DTMF for free. Soon thereafter, phones always sent out tones in response to the buttons; it was not necessary to simulate the clicks any more.
What does your cell phone do when you push those buttons? It gathers them up as digits, then it looks up the number in a central database, finds the cell phone associated with that number, determines the location of that cell phone, charts a path to that phone, and connects the call. However, when the call is established, then those buttons sing once again. After all, you might be entering your credit card into an automated payment system, to pay your water bill. Each digit sends the same notes as it did in 1963, non-harmonic tones that will not appear in the music that is playing in the background.
In days of old, the phone bill included a list of calls made, and the charge for each. Local calls were free, but most of the time you were calling someone in another central office, a toll call or a long distance call. An hour long call with a close friend across the country could cost ten dollars. Time of day was a consideration. We waited til after 11 PM to call our relatives in Utah, because the rates were cheaper. It was 9 o'clock their time, so they didn't mind.
When I walked into college in 1978, there was a phone affixed to the wall. I think it was a rotary phone; they hadn't upgraded to touchtone yet. I signed up for service, along with my roommate. Together we were responsible for the phone, and all calls made thereon.
Each month we received a bill. He went through it and assigned each call to him or to me. He then totalled up the charges. I paid my portion, and he paid his. That's how it use to work.
A modern cell phone lets you call anyone, any time, and talk as long as you like, with no additional charges - unless you make an international call, and then you might see a charge for that particular call.
Sometimes a feature appears by accident. The early mechanical switches had unavoidable delays in their operations. After the phone went on-hook, it took several seconds, sometimes 30 seconds, for the call to drop. People found that they liked this feature. If Bob called Alice, and she answered in the bedroom, she might not want to have a long conversation in the bedroom. She might be cooking, and would prefer to use the extension in the kitchen. So she hangs up, runs to the kitchen, and picks up the phone, and Bob is still there. By the 1950's, people expected phones to work this way.
When I went to work at Bell Labs in 1982, calls were controlled by computers. They could easily disconnect the call upon hangup, but we were told not to do that. We wrote special software to introduce a 30 second delay, as people expected. This only applied to the called party. The caller was on the extension he wanted to be on, or so we assumed. After all, he placed the call. If he hung up, the call dropped instantly. But if the called party hung up, she had 30 seconds to pick up the phone, or run to another extension, and the call would still be there.
This is meaningless in the era of cell phones. There isn't another extension, there is just your phone, and it travels with you, wherever you are. Thus a cell phone call drops whenever either party hangs up.
I do however miss the satisfying sound of slamming the receiver down on the cradle, and knowing for sure that I have hung up. I can then say, “Wow! My boss is a pontificating bastard, a steaming pile of cow dung.” This is risky on a cell phone. Perhaps I thought I hung up and didn't. Perhaps I pressed the wrong button, or it didn't register my tap. Perhaps he is still listening as I speak my mind. I have to be careful. But in days of old, once I slammed that receiver down, I knew he was gone, and I could vent freely.
Also, there is a satisfying bang, and jingle from the bell, as the receiver slams down. If you're my age, you know the sound. I would like to have an app on my cell phone that sends this sound to an unsolicited caller, perhaps a salesman, or bill collector, or scammer, and then hangs up. That would get the point across. It's not as satisfying as physically slamming the receiver down, but still pleasurable.