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.
MobiGater is a device which transfers your Skype calls to your mobile phone without the use of SkypeOut credits. It connects to your cell phone via a SIM card placed inside it, and using a USB cable to your PC and Skype.