Why not answer the phone with 'Hi' rather than 'Hello'?

Answer 1

Normally, when someone answers the phone with 'Hello', people can understand them and hear them more clearly, mainly because 'Hello' has two syllables, and 'Hi' has only one. If you were to answer the phone with 'Hi' instead, people might miss what you are saying and ask you to repeat it, if you say 'Hello', it's no bother at all.

Also, if you are answering with 'Hi', it is informal, and you say 'Hello' as a question when picking up the phone, not a greeting as you would say when you see someone you know, because a normal phone conversation will go something like this...

"Hello?"

"Hi, it's ----"

"Oh, Hi ----!"

And you would say something more infomal if it's a friend or a relative or someone you know well.