I deal with customers in other countries daily - slowly I'm converting them all to Skype - we can talk, chat and send files all at the same time.
I have voicemail on Skype.
I call whoever else has Skype for free.
I can do a conference call with a few clicks of the mouse.
I can forward my Skype calls to my cell phone and pay just the Skype-out rate.
Those without Skype, I have to pay the 2.2 cents (my father in law who is 93 and who I will not get converted now, and a few others).
The Skype Business plan let's me manage four or five Skype accounts from one place.
Toll-free numbers are free - I don't pay for calling 800 numbers which we call frequently for technical support.
Our business phone bill has come down from around US$450 month to around US$60 per month.
I'm smiling.
Yes, there are other voip companies, but I think Skype is top of the log for now, both for the individual user, as well as for the business user.
(I'm going to kill myself if my main computer crashes .. )
And I forgot to say, the quality is excellent for the most part .. now and again a call is garbled, but it happens very infrequently.