Or use Google Talk, for fuck's sake. The protocol is open, and the service is very reliable. I got all my friends running iOS to get Vtok, and now they can chat with me too. And you don't have to be on a Mac to use it from a computer - just log into Gmail or use any Jabber/XMPP client you want. I haven't used any other messaging service in over 5 years.
The only thing I use Google Voice for is the one or two friends still using dumbphones.
Google Talk is also the protocol for chatting on Google+ (That is, it's the same chat as on Gmail). I've used it for a while to talk with friends around the globe; it's a great place to centralize quick chats/messages and video hangouts. I get Google Talk messages on my phone, and I can leave messages for them to see next time they log on to Google+ or Gmail. It's pretty sweet.
No, I mean the Google Talk mobile app allows you to make voice and video calls. I'm not talking about calling phones, I mean you can call other Google Talk users. You can of course use Google Voice on Android to make international phone calls if you want, as well.
You should be able to call any XMPP (Jabber) users if their server is federated (and they have a client with XMPP/Jingle support of course). I.e. not only to the users of Google's XMPP server.
I don't see what your point is. This conversation was never about phone calls in the first place. It was about VOIP to VOIP calls, which are of course completely free and unlimited to anywhere in the world if you use Google Talk.
The only thing I use Google Voice for is the one or two friends still using dumbphones.