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.
SunComm Technology Co., Ltd. Core members have been engaged in the communication & networks industry since 1977. Their main products in 2009 focus on GSM, VoIP, 3G Devices.