Most providers charge one price for calls within their network -- usually free -- and higher prices for calls out of their network, and even more for international calls. Why? Because it costs more to use the traditional public landline network to make international calls. Remember, one the main functions of your VOIP provider is to make sure you can all anyone -- including people on the public, switched network and other VOIP networks. That's where the cost comes in, and they pass that cost back to the consumer with higher rates.