What is GSM Gateway?
GSM Gateway is a device connected to the fixed phone or fixed telephone exchange which by a SIM card directs calls from fixed telephony to mobile telephony. When a user calls a mobile phone from his fixed number, the call bypasses the fixed telephony network and is directed directly to GSM network. In this way, although a user is calling from a fixed phone, he is making the call within the mobile network.
In this way you can save up to 70% on your fixed phone bills.