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.
SIP & Data Service Provider: We offer SIP Trunking for data services and support VOIP phone service with full QOS Data Connections, SIP & Data Services, SIP Trunking for Data Services Optimized for Voice.