How operators connected calls by hand
A telephone exchange is the building where the telephone lines of a town meet, so that any two of them can be joined for a call. Before machines took over, operators did the joining by hand at a switchboard. You lifted your receiver, an operator asked "Number, please?" and plugged a cord between your line and the one you wanted. The first commercial exchange opened in New Haven, Connecticut, in 1878, and London's last manual exchange worked until 1960. Today software does the joining.
Purple: your call and the parts it usesKey
- Purple: your call and the parts it uses
- Lit lamp: a line asking for the operator
- Fallen drop: a line asking for the operator
- Lifted receiver: on the phone
1920s · central battery · every line quiet
Press a button, or click your telephone to lift it.Press a button, or tap your telephone to lift it.
The same steps in both. What changed is how you call the operator and where the power comes from.
Anatomy of a switchboard: one call through a manual telephone exchange of the 1920s and of the 1880s. The drawing is not to scale.
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Follow one call
Press Play to watch the call, or scroll down and the drawing follows you one step at a time. Try it, under the drawing, makes your own call.Press Play to watch the call, or Next to go one step at a time. Try it, under the drawing, makes your own call.
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Step 1 of 6
You lift the receiver
You want to call your friend, number 47. In the 1920s you only lift the receiver off its hook. That lets current from the exchange's battery flow round your line, and a small lamp lights over your jack on the operator's board. In the 1880s you first turn the crank on the side of your telephone. It sends a ringing current down the wire, and a small flap over your jack, called a drop, falls.
Why did the 1880s telephone need a crank and batteries?
The crank turns a small generator, called a magneto, inside the telephone. The current it makes is what releases the drop at the exchange. The batteries in the box under the telephone powered your microphone.
From late 1893 the Bell System opened common battery exchanges, where one battery at the exchange powered every line. Lifting the receiver was signal enough, and the crank and the batteries left the house.
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Step 2 of 6
The operator asks: "Number, please?"
An operator sees your lamp, or your fallen drop. She pushes the answering plug of a pair of cords into your jack, flips a key to put her headset on your line and asks which number you want. In the 1920s your lamp goes out as her plug goes in. You say 47. Look inside her position below.
Inside an operator's position The position
- 1Line lamp
- 2Jacks
- 3Answering plug
- 4Calling plug
- 5Cord lamps
- 6Keys
10,000 jacks and more could sit within reach of one operator, one for every line in the exchange.
- 1Drop
- 2Jacks
- 3Answering plug
- 4Calling plug
- 5Clearing drop
- 6Keys
How many lines did one operator look after?
About 100, a textbook of 1905 reckoned. On the busiest business lines it could be as few as 10, and where people seldom phoned, up to 400.
The first operators were men and boys. By 1881 young women were replacing them, the Bell System's own history records.
Sources: Kempster B. Miller: American telephone practice (1905); Bell Telephone Laboratories: a history of engineering and science in the Bell System, the early years (1975)
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Step 3 of 6
She tests jack 47 and plugs in
Above her answering jacks sits a field of jacks with one for every line in the exchange, number 47 included. Before she plugs in, she touches a plug tip to the rim of jack 47. A click in her headset means your friend is already on the phone. No click, and she pushes the calling plug in.
Who came up with the click?
Charles Scribner of Western Electric, around 1883. Before his busy test, an exchange needed a separate board to show which lines were in use.
The field of jacks is called the multiple. Every line appears again at every position, so each operator can reach any line from her stool. Later boards put more than 10,000 jacks within reach of one operator.
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Step 4 of 6
She rings, and your friend answers
She pushes the key the other way. Ringing current runs out of the exchange, along the poles and into your friend's house, and the bell on the wall rings. Your friend lifts the receiver, and the two of you talk through the operator's pair of cords.
How did she know when you had finished?
On the 1920s board each plug of the pair has a small lamp on the shelf. It stays dark while that person's receiver is off its hook and lights when they hang up, so she can see when your friend answers and when either of you puts the phone down.
With these signals, the Bell System's history says, every call by 1900 came down to two plugs and one key.
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Step 5 of 6
You hang up, and she pulls the cords
In the 1920s, when you both put your receivers back, the two cord lamps light and the operator knows the call is over. In the 1880s you turn the crank once more to ring off, and a drop on her shelf falls. She pulls both plugs, and weights under the shelf draw the cords back into place, ready for the next call.
How many operators did all this take?
In 1902, as common battery boards spread, the Bell System employed about 30,000 operators, roughly 22 for every 1,000 telephones.
By the First World War it was about 100,000. Better boards had brought the share down to about 15 for every 1,000 telephones, but there were far more telephones.
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Step 6 of 6
A long-distance call takes more operators
To call the city, your operator passes your call to the long-distance position at the end of the board. The long-distance operator writes the call on a ticket, plugs into the trunk line, a line between two exchanges, and calls the city's exchange, where another operator rings the number you want. In 1920 that took 13 minutes on average in the Bell System.
Why did it take so long?
Partly because of the tickets. Operators wrote down and timed every call, and in large offices the tickets travelled between operators on conveyor belts or with messengers, a few of them on roller skates.
From about 1925 a single operator handled the whole call instead of passing it between specialists, and she answered with the words "Long Distance". By 1929 the average was down to 2.6 minutes.
Inside a position: the 1880s and the 1920s
The operator's steps stayed the same: answer, ask, test, plug in, ring, pull the cords. What changed is how the call reaches her and where the power comes from.
One operator's part of the board, taken apart in the order she uses it. Point at a part, or tap it, to see what it does.
Magneto board, 1880s
Central battery board, 1920s
The position
- 1Drop
- 2Jacks
- 3Answering plug
- 4Calling plug
- 5Clearing drop
- 6Keys
The position
- 1Line lamp
- 2Jacks
- 3Answering plug
- 4Calling plug
- 5Cord lamps
- 6Keys
10,000 jacks and more could sit within reach of one operator, one for every line in the exchange.
How you call the operatorBell Telephone Laboratories
Turn a crank
Your telephone sends a ringing current
Lift the receiver
Taking it off the hook is signal enough
What the operator seesBell Telephone Laboratories; Kempster B. Miller
A drop
A flap that falls over your jack
A lamp
It lights over your jack
Power for your voiceBell Telephone Laboratories
In your home
Batteries in a box under the telephone
At the exchange
One battery for all the lines
When the call endsBell Telephone Laboratories
You ring off
Crank again, and a drop on the cord falls
Lamps light
The cord lamps light as you hang up
Switchboard in numbers
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120,000
A board for 6,000 lines with 20 sections carried 120,000 jacks, because every line had a jack at every section.
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150,000
In 1965, with almost every telephone dialling its own calls, the Bell System still employed about 150,000 operators, about as many as in 1925.
How it came to be
- 1878
The first exchange
On 28 January, George Coy's New Haven District Telephone Company opens for business in Connecticut. Its switchboard connects 21 subscribers, each paying $1.50 a month.
- 1880
Cords on a shelf
The "Standard" switchboard puts a keyshelf in front of the operator, with double-ended cords that weights pull back into place. Every manual board after it keeps the shelf.
- 1881
Women at the board
Young women are replacing the men who ran the first boards. A rig that carried an operator's transmitter on her shoulder weighs 6 pounds, about 2.7 kg. It is too heavy for them, and engineers look for lighter sets.
- 1891
A machine instead
Almon Strowger of Kansas City is granted a patent for an automatic telephone exchange, one that connects a call without an operator.
US Patent 447,918: Strowger, automatic telephone-exchange (1891)
- 1893
Power from the exchange
The first common battery exchanges open late in the year. One battery at the exchange powers every line, and from 1894 small lamps start to replace the drops on the board.
- 1960
London's last manual exchange
On 5 October the switchboard at Enfield, in use since 1925, is used for the last time. It was the last manual exchange in London, and Enfield became automatic in 1961.
Science Museum Group: CB1 manual switchboard from the Enfield telephone exchange, 1925 to 1960
Where Voxbi fits
Voxbi, a cloud phone system hosted in the European Union, routes calls with call flows instead of cords, and shows a receptionist who is free before a transfer.
See it in Voxbi