[temp84858696945]

Saying just "Hi" or "Hello" is asking for a synchronous chat, whether by text or by voice.

Lots of people prefer talking to people rather then writing each other letters.

Yes it's arguably less efficient, but lots of things that people do are inefficient, and if they prefer that means of communication it doesn't really hurt and in my mind is just polite to oblige them.

[ilyagr]

Then you can say "hi, do you have a moment for a quick chat? I'm free until 4".

Be aware that this can cause a heart attack or panic if you are in a position of power over the recipient.

Saying something like that to your manager can work wonders, though.