On the 10th of March 1876, Scottish-Canadian Alexander Graham Bell, in his Boston, U.S.A. laboratory, first successfully transmitted speech using telephony, saying "Mr. Watson, come here! I want to see you!"
On St. Valentine's Day (February 14th) 1876, American Elisha Gray had submitted to the U.S. Patent Office a caveat for a patent for a liquid transmitter. A caveat is a notice of an intention to submit a patent. However, Bell submitted a patent two hours later the same day. It was a patent for something different but related.
What Bell used for the first phone call was the liquid transmitter as described in Gray's caveat but also Bell's own patented invention of an electromagnetic receiver.
Bell and Gray went through a protracted legal dispute. Eventually, Bell's patent withstood Gray's attorneys' challenges.
Check out the Wikipedia entry, Timeline of the telephone. The timeline of the telephone shows the portraits of more than 10 individuals involved with various ideas and inventions related to the development of early telephony.
The timeline demonstrates one of the principles of invention that, among others, is excellently explored in James Burke's brilliant, landmark television documentary series Connections (1978): the concept that no inventor works in isolation. All inventors borrow upon the work and ideas of others, and often history gives short shrift to the "others."
That doesn't mean genius doesn't exist and that the wrong person always gets ultimate credit or that all those we deem to be great inventors are usually or always nasty fame-seekers, perhaps even unethical ones, too. It means this:
Scientific discovery is a complex process involving connections between myriad ideas and people. And as Burke shows in Connections, those connections can sometimes reach back centuries.
Photo #1 (click to enlarge), Alexander Graham Bell makes the first phone call from New York to Chicago in 1892. I cannot find online a date for when the call was made, only the year. Do you know the date? If so, tweet it, please: @isebrand.
Photo #2 (click to enlarge), Bell demonstrating with a 1876 prototype. I think it is not the one used to make the first call, but I'm not very certain of that.