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.
Peneo is a leading-edge technology firm specializing in VoIP (Voice over IP) solutions to lower telecom costs for residential consumers (B2C), commercial businesses (B2B), and callshops/Internet cafes.