<Li> 25 October 1877: the article in the Scientific American is discussed at the Telegraphenamt in Berlin </Li> <Li> 12 November 1877: The first commercial telephone company enters telephone business in Friedrichsberg close to Berlin using the Siemens pipe as ringer and telephone devices build by Siemens . </Li> <Li> 1 December 1877: Western Union enters the telephone business using Edison's superior carbon microphone transmitter . </Li> <Li> 28 January 1878: The first commercial North American telephone exchange is opened in New Haven, Connecticut . </Li>

When did the first phone go on sale