Voip PC Phone does not rely on Third-Party Vendors or Special Internet Websites to make calls. All you need is a headset and microphone to make a call.Voip Phone works only on LAN and DSL connections. The minimum bandwidth required is 64Kbps (continuous).Before making a call, press the refresh button to make sure of your I.P. Address. When making a call over a DSL connection, connect first and then run the application to ensure a correct return I.P. Address.On a LAN connection the I.P. Address is your network card address. On a DSL connection, the I.P. Address is the address your I.S.P. provides automatically when you connect.Please Note. - If you are behind a firewall, allow access on ports 8500 and 6767 - TCP/UDP to receive and transmit calls.