The MUST HAVE program for your BlackBerry:
BBCalls
You will love it.
It just initates the call over the internet. The actual call works on the normal GSM/IDEN/CDMA network. So BBCalls runs on all current BlackBerrys in all countries. You can for example make a FREE CALL from your BlackBerry in the states to a mobile phone in the People's Republic of China. Isn't that great?