The story behind the usage of word "Hello" while answering telephone calls:
The word, "hello" as a greeting while answering the phone call became familiar soon after the invention of the telephone. Alexander Graham Bell's invention of telephone gave us two new words telephone and hello.
There are many different stories behind the word hello. It is said that initially the inventor used the word Ahoy (this is a signal word used to signal a ship or boat). The use of hello as a telephone greeting has been credited to Thomas Edison. According to one source, Edison expressed his surprise with the word, "Hullo". Hullo is the exclamation to call attention, an expression of surprise, or a greeting. It is said that the word hello is derived from hullo.
Later in 1880's the telephone operator girls were called as "Hello-girls". Now this word is used to make sure the person who picks the phone call can here the voice from the other end of the phone.