This was already possible years ago. I used a patched Psi (XMPP) client for VoIP...

		gst on July 30, 2012 \| parent \| context \| favorite \| on: Google Talk for Developers This was already possible years ago. I used a patched Psi (XMPP) client for VoIP calls to Google Talk clients in 2006 (IIRC).