When a New Yorker calls one of the city’s principal telegraph companies on the phone to send a wire, he now sets in motion a super-robot so swift that a stopwatch often cannot time it.

Within the short space of one second, on the average, he hears the answering voice of one of 110 girls, who sit at desks as shown in photo above. This is made possible by the “automatic call distributor, ” called one of the most important inventions in recent years.

This intricate machine, a maze of contacts and wires twice as tall as a man, instantly detects an incoming call, hunts for and finds an unoccupied typist, plugs in a connection to her desk, and signals that there is a message for her to take. If she fails to respond, the robot switches the call to another typist.

Similar “robots” are planned for Chicago and Boston, according to Western Union officials who installed the first one.

  1. Torgo says: June 18, 20085:23 pm

    I was hoping to see something like Robby the Robot on rollerskates.

  2. g662 says: June 20, 20086:56 am

    Oh my!, I program ACDs as part of my job (PBX engineer) and even I didn’t know their predecessors were *that* old. Somehow I thought they had originated in the 1950s as an offshoot of the crossbar switching system. The machine in the picture appears to be all-relay.

    Now if all it does is “hunting,” seeking the first vacant person in numeric order all the time starting from the first to the last, that would not be a major achievement: hunting has been possible since the early days of Strowger switching.

    However, true ACD is far more of an achievement: it is as if there is a stopwatch above the head of each operator, and as soon as she hangs up from one a call, the stopwatch starts ticking. Then when the next call comes into the ACD system, it looks for the person whose stopwatch shows the longest time since their last call. This assures that all the operators get as much time as possible between calls to wrap up whatever business is needed e.g. signing or handing in a form, etc.

    There are a few other algorithms for distributing calls, such as UCD (Uniform Call Distribution) which does away with the stopwatch and just directs the calls around a circle “round-robin” style: whoever got the last call doesn’t get another until each other operator has gotten a call. That’s clever, but not quite as clever as ACD.

    As recently as 15 years ago, ACD machines were specialized for the purpose and even the early computerized ones were expensive as h—. Nowadays, ACD functions are built into many high-end PBX systems at no added cost. Even a small office with a few employees can afford to have this capability.

  3. JMyint says: June 20, 200810:16 am

    This is really pretty easy to do with an electro-mechanical device called a ‘selector’. What you want is for each of the 110 girls to answer a call before the first one gets another and you don’t want to have anyone waiting too long on the line for a connection.

    A selector is a sort of electro-mechanical memory. It is usually circular (some are straight but they wouldn’t be suitable for this application) and set with spring loaded pins protruding from one side. Each pin is hooked to a solenoid that is controled by the receiver switch on each phone. Then there is a read arm with a contact switch and a solenoid. When a call comes in the read arm moves to the first protruding pin, the contact switch hits the pin, and rings the associated phone. When the person answers their receiver switch deactivates the solenoid on the pin and the solenoid on the read arm fires pushing in the pin and then moves just past it. When the next call comes in the read arm moves to the next pin and repeats. When the call is completed and the user hangs up the receiver switch fires the solenoid on the pin, pushing it back out. To prevent the selector from just ringing away at an empty desk a timer could be set to push in the pin after a certain number of rings (say three) and move the arm to the next pin, and since the receiver is down on that phone the pin solenoid would fire the pin back into place. Once all 110 phones have been selected the read arm will go to the next available line when called. So if phones 1, 2, and 3, are still engaged then the selector will go to 4. The only time a person would get a call a soon as they hung up is on the occassions that all the lines are busy, or the rare chance they just happened to be the next available line. Other wise the calls should be evenly distributed throughout all the operators.

  4. George says: August 24, 20081:38 pm

    Hello, your telegram is as important to us as it is to you. Please hang on and the next available ‘girl’ will take your call.

    All calls are recorded so we can pick up stock tips or add a laugh track and put it on YouTube.

    Please select from the following menu:
    – If your telegram is to congratulate someone, dial 1
    – if someone has died, dial 2
    – if you need Mr. Watson, dial 3

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