You could type the history of telephones into a search engine like yahoo or google or check your local museum for information?
http://www.plantronic.com/north_america/en_US/lifestyle/#location:home;devices:1;10:2;20:1;40:3;50:2;70:2 http://www.plantronic.com/north_america/en_US/lifestyle/#location:home;devices:1;10:2;20:1;40...
C.Ds, Books, Internet, People, Dvd's, PC Cd's 118 118, Teachers, Radio, A Wiki. .
www.varsity.com
Wikipedia, the Internet, or even answers.com can tell! Books and newspapers help a lot, too.