Concerning practical implementation, the VoIP gateways have proven to be the best. Many companies are successfully using the IP telephony thanks to its two main characteristics
Decrease in international and long distance call cost expenditures
Stable communications between company’s offices throughout different cities and counties
Now with "NuovoVoip" by TelefonicaWeb.net ,you can call with internet telephony rates from any landline or mobile, without having to use internet, 3 g, wifi, etc