I have been one of the first users of the beta service, and am very fond of it, I even have the Voice app for my moto droid. After speaking with verizon representatives, when I first began using the service, everyone agreed that “using the voip service Google Voice means that you don’t use your regular monthly minutes.” Let me explain how this works:

Once configured, you make a phone call, and you see the special phone call banner:

The person your calling appears to receive a phone call from your google voice number, and you appear to make a call using magic google internet fairy dust. Verizon/Google advertise this feature as true Voice over IP; i.e.  your phone “dials” non-traditionally over a data network, making a phone call without actually using your monthly minutes.

Unfortunately this is simply wrong. Every once and a while while using GV I have seen a new banner saying “Call being completed through 347-227-2000.”

Calling this number yourself is normally quite frivolous. You see you are calling one of google’s computers, this is a google’s many “voice” access phone numbers. With the right authentication your phone makes a regular phone call to this number and then google completes your  phone call for you (at no charge). As a result, my phone bill specifies that I spoke with 347-227-2000 for 190 minutes this month! While this hasn’t caused me to suffer any additional charges, it might have, since I thought I used those 190 minutes “for free” (by free I mean, that it was included in the cost of my data plan).

In order to remedy this, I simply have added that access number to my friends and family list, making phone calls over google voice “truly free,” (unless and until google changes my access number). Of course then I need only change the number on friends and family.