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.
NumberGroup provides business quality VoIP services to wholesale operators and SIP Trunk customers worldwide. We have over 1,000,000 UK and Internaiton telephone numbers are are a license UK operator with direct PSTN connectivity.