Telephone
The use of hello as a telephone greeting has been credited to Thomas Edison; according to one source, he expressed his surprise with a misheard Hullo.[9] Alexander Graham Bell initially used Ahoy (as used on ships) as a telephone greeting.[10][11] However, in 1877, Edison wrote to T.B.A. David, the president of the Central District and Printing Telegraph Company of Pittsburgh:
Friend David, I do not think we shall need a call bell as Hello! can be heard 10 to 20 feet away.
What you think? Edison - P.S. first cost of sender & receiver to manufacture is only $7.00.[12]
By 1889, central telephone exchange operators were known as 'hello-girls' due to the association between the greeting and the telephone.[11]