Who coined the greeting, "Hello" used for answering the telephone?

Funny you should ask this.
I have just completed a 25 year project.
My family tree.

I managed to trace my family (on my dad's side) to a bloke called Clive who was born 15th June 4476 BC

I have proof that he was the first person to use the word - when his mum called "Clive" and he answered "Hello".

Mind you, she didn't understand what he said because they were Chinese, but the word caught on.

So, my great great great etc grandfather Clive patented the word.
This means that every person who has ever said the word, "Hello" since then has to pay Clive 1 cent.

Unfortunately, Clive died (well, he was eaten by a dinasaur actually) in 4475 BC BUT being his next of kin . . . . . I estimate that I'm owed . . . . phew, loads.

As from next Thursday I'm going to stand in my local shopping centre and everytime I hear someone say "Hello" I'm going to collect.

Yeh

While the origins of the word "hello" are alternatively suggested to be the English words "hullo" (a slangy term for expressions of surprise, dating to early 1800s) or "halloo" (a call out to grab attention dating back to Shakespearean times), there's little doubt that Thomas Edison played the key role in popularlzing "Hello" as the way to answer the telephone. As the below linked article suggests, the word may be due to Edison's misspelling or alternative spelling of "hullo." Hope this helps. :)

me I sware!

Its pronto in Italy