I too found this thread while looking for a "answering machine" app, and not for the possibility of "free voice mail", but because I miss the old school days when one could screen ones calls (before CallerID). I was hoping someone had made an app that could allow you to play a message to the caller and be able to listen to the caller's message in real time, and if you choose to, talk to them. I think that's what the person was looking for, or maybe not (I kinda skipped over all the other nonsense about whether voice mail is free in Croatia... focus people, focus!)
Anyway, thats why I'm here. Maybe someone knows someone that can write an app for that. Just remember you heard it here first!
Any sufficiently advanced technology is indistinguishable from magic. - A.C. Clarke