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.
Level 3 (Nasdaq: LVLT) is an international communications and information services company and is headquartered in Broomfield, Colorado. The company operates one of the largest communications and Internet backbones in the world.