According with a business telephone systems company, the concept of implementing a telephone, a telephone through which he could connect with another phone, was proposed by Edwin T.Holmes, who led a plant of this kind in 1877, in connection with your burglar alarm system in Boston.

In this system, the pair of wires coming out of our van on telephone poles, outdoors or underground, covered with insulation to a building where hundreds of cables converge to such interconnection explains a business telephone systems company.

According with a business telephone systems company, in central operators, who later established the technological advancement, there were many employees, sitting next to each other in front of a telephone switchboard.

Each of these employees was provided with a receiver and a transmitter, located in front of them in a panel, thus leaving both hands free.The front of the box consisted of a large number of small holes called "jacks" and next to each hole was placed a small electric lamp.Each of these holes represented the end of a telephone line.Between the operator and the vertical face of the box was a narrow shelf, where hundreds of terminals protruding through the tip of metal.These are called "pins", and were attached to the ends of flexible cords.

When a subscriber dismounted his receiver off the hook, caught one of the tiny table lamps, and the nearest attendant took one of the pins and inserted into the jack near the light bulb.The lamp was extinguished, but at the same time struck another on the bench next to the flexible cord.The operator then close a switch on the bench or shelf that connects your phone to the subscriber and said: "Central" Upon receiving the number desired, the operator took another plug, connected it under the bench to the firstThe inserted into the jack which belonged to the order number and pressed a button, the phone rang the person who called.

As soon as the person to answer the call, picked up the receiver of your phone, adjacent to the first flexible lamp went out, telling the operator that had been made the connection request.As this was the phone line disconnected after receiving the desired number, the operator was free to establish other connections.When the subscriber in a line back to hanging up the phone receiver, adjacent to the flexible lamp was lit for the operator removed the plug, shutting down the lamp, and turned to put the item on the shelf.In an active telephone table lamps were continually on and off, accompanied by the so-called "central" And the ticking of the pins.

The other half, whose employment increased after, as the automations were gradually replacing the operators, was that in which the connections were made through an automatic machine, which was run by the person making the call.Instead of waiting for the phone to ask the number you want, the subscriber, in a machine, connect your phone with any other party by turning a dial numbered with successive numbers of the desired phone number.The machine automatically connects the two phones, and the caller can then directly to ring the phone ringing the other party.