Has anyone had any luck doing this? Our users basically want to be able to travel internationally and not incur any additional charges. I've seen a few 3rd party apps out there...none of which are 100% free of roaming charges.
Using 3G or EVDO maybe, but not EDGE. Plus a cell phone system is not made for VoIP. Latency is one issue, data rate/bandwidth is another, and the connection itself is a major issue.