I have Blackberry Curve 8320. In May 2009 I stayed at a hostel in Milan, Italy with free wi-fi. The wifi requires a password but I can't recall what kind of security authentication (WEP, WPA, TKIP, etc). Since I was a hostel guest, I can use the wifi freely.

I walk up close to the wi-fi transmitter, set my Blackberry to "Manage Connections", disable "mobile network", enable "wi-fi", follow the wizard to look for wifi, enter password. Viola! Within 1 minute I have "UMA" status on the right top corner. I called friends and parents in USA and sent couple text messages "Guess... I am in Milan now, bla bla bla...". The minutes and SMS were billed as domestic usage. No international roaming or surprise bill whatever.