Use SmartDial to route calls through calling cards or VOIP box.
SmartDial can be setup to manage multiple calling cards to save on long distance calling. After the setup, all you have to do is dial your destination number either from your address book or your recently called list. If setup properly, SmartDial will route the call by calling the access number and entering the PIN if any.
If you have a VOIP device such as Vonage or Fritz.box by AVM, you can call International at low rates by setting up SmartDial to call your VOIP device and then dial the destination number.