Well my "data" is based on what I've experienced. I've never claimed anything other than that. I'd love to collect more detailed data on what's going on but I don't exactly have access to Google's servers. Whatever the case, I have read about problems other people are having and the service is far from complete. Believe it or not, but there are actually other people that have run into similar bugs (especially the "can't hear" bug).
Anyway, I can make international calls using my mobile phone without Google Voice and I get connected without trouble. And I can hear the people I call. Connecting to the right person and being able to hear each other are kind of critical for a telephone/VoIP service, by the way.
If Google Voice is merely making use of landlines, towers, etc. then surely it should behave exactly like my mobile phone, right? At the very least people should be able to hear me, yes? I haven't run into either problem with my wireless provider.
Skype works just fine when using my same mobile phone and when calling the exact same international number. So I call shenanigans on your shenanigans.