Professional

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.[6] Alexander GrahamBell initially used Ahoy (as used on ships) as a telephone greeting.[7] However, in 1877, Edison wrote to T.B.A. David, the president of the Central District and PrintingTelegraph 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 ofsender & receiver to manufacture is only $7.00.[citation needed]
By 1889, central telephone exchange operators were known as 'hello-girls' due to the association betweenthe greeting and the telephone.[8]
Hullo
Hello may be derived from Hullo, which the American Merriam-Webster dictionary describes as a "chiefly British variant ofhello,"[9] and which was originally used as an exclamation to call attention, an expression of surprise, or a greeting. Hullo is found in publications as early as 1803.[10] The wordhullo is still in use, with the meaning hello.[11][12][13][14][15]
Hallo
Hello is alternatively thought to come from the word hallo (1840) via hollo (also holla, holloa,halloo, halloa).[9] The definition of hollo is to shout or an exclamation originally shouted in a hunt when the quarry was spotted:[9] Fowler's has it that "hallo" is firstrecorded "as a shout to call attention" in 1864.[16]
It is used by Samuel Taylor Coleridge's famous poem The Rime of the Ancient Mariner written in 1798
And the good south windstill blew behind,
But no sweet bird did follow, Nor any day for food or play Came to the mariners' hollo!
Hallo is also German, Norwegian, Dutch and Afrikaans for Hello.