Time to delve a little deeper.
VoIP or Voice over internet protocol; having read the intro to IP, you may now be starting to understand VoIP. It's a way of turning a voice into a data packet, sending it over a broadband connection then putting it back together at the other end and delivering it to a handset as a recognisable voice, very very clever!
The big difference between making a VoIP phone call and sending an email is that the voice call has to happen instantly in order for the conversation to flow. If an email arrives a second late it doesn't really matter, if a word arrives a second late; the conversation doesn't make any sense.
