I believe the international rates are way more expensive. But i haven't searched for it. I wanted a HK and Macau number and found it way too expensive. Calls out of China are more expensive than out of HK.
If you have a computer at hand, a nice option is voipcheap, where you can initiate a callback to many countries free. Connection charge is 5 Eurocents per (attempted) call. If you use their softphone software, there is no connection charge. The call quality varies, but is most of the time very good and way better than Skype out. Calls to Thailand also are 1 Eurocent, which is outstanding.

www.voipcheap.com, www.voipbuster.com, www.lowratevoip.com
all the same company with different tarifs.