It's also very important to have a good sound card in your computer and a decent microphone.

I have Via Voice by IBM from 1999 still works fine when i need to use it.

But I did get a new motherboard with built in sound and it does not work at all with my microphone.
I still had my older sound card so put it in the puter and I can switch between the 2 cards when i need my mic.

My mic is a Plantronics headset type.