By using Portech SBK-32 expander for 32 SIM-cards, you can increase the number of channels in the Portech MV-37X GSM VoIP gateway series using the Internet.
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