He was also responsible for several technical innovations of Morse's system, particularly the sending key and improved recording registers and relay magnets.
2.
The first commercial automatic telephone exchange, designed by Almon Brown Strowger, opened in La Porte, Indiana on 3 November 1892, and used two telegraph-type keys on the telephone, which had to be operated the correct number of times to control the vertical and horizontal relay magnets in the exchange.
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