Almon B Strowger, the man behind automatic switching and dial telephone, was born in 1839 in New York. His constant feuds with
telephone exchanges inspired him to develop an automatic switching and the dial telephone.
Telephone exchanges made their appearance in 1878 in Connecticut to overcome the difficulty of running lines directly from each instrument to every other with which a customer might wish to connect. Telephones were connected to a manually operated central switchboard. A caller cranked a lever to electronically alert the operator who on learning which party the caller wanted, connected the two phones by plugging in the appropriate jacks.
In 1887, Strowger along with some technicians started working to find a way to bypass operators. The working model of the automatic switching apparatus was developed. Patented in 1891, this step by step or SXS system replaced the switchboard operator. It was made from a pencil, some pins and a small cardboard box that had once stored detachable shirt collars.
Inside the round box, there was a pencil standing upright in the centre. Pins were arranged in a spiral around the pencil. As Strowger rotated the pencil, these pins made contact with other pins he had stuck to the inside of the collar box. By raising and turning the pencil, Strowger could alter the contact points, creating a number of different configurations.
This is considered to be a precursor of the touch-tone phone. It had three
buttons–one for hundreds, one for tens, and one for units. To call the number 547 one had to push the hundreds button five times, the tens button four times, and the units button seven times. In 1891, Automatic Electric Company was founded to exploit the Strowger switch. By 1896, he had developed a rotary dial to generate the pulses.
The first Strowger exchange was installed in La Porte, Indiana, in l892. Though it worked, it was a less-than-perfect solution. The nature of equipment used in such exchanges was prone to breakdown. A great technological advancement though, Strowger’s switch faced another difficulty. Some users still objected to setting up their own calls. Two lobby groups championed the cause of manual exchange. One group–not sharing Strowger’s antipathy to manual operators–appreciated the personalized services provided by manual exchanges. The other argued that manual exchanges were more cost-effective. But eventually, as telephones became more popular, manual exchanges were simply unable to handle the volume of calls. Automation was on its way.
He constantly kept working towards improvements to his
system. By l896, he had reduced the wires to three and replaced the push-button arrangement with a dial. Eventually, Strowger’s system needed only one pair of wires and a metallic return circuit between the telephone and the exchange–to carry both conversation and dialing information. That arrangement worked so well that it is still in use today.
Interestingly, Strowger had earlier rejected the thought of dial phones but quickly reacquired interest when threatened by a telephone operators’ strike. A boon from adversity?
Strowger sold his patents to his associates for $1,800 in 1896 and his share in the company for $10,000 in 1898. He died in 1902. In 1916, his patents were sold to Bell System for $2.5 million. Bell introduced dial phones in Norfolk, VA, in November 1919. His brother, Walter S Strowger, carried forward the development.