GSM gateways are physical systems or devices that link GSM networks to VoIP (Voice over IP), PSTN (Public Switched Telephone Network), or PBX (Private Branch Exchange) systems. They are also referred to as GSM voice gateways or GSM gateway devices. In essence, it enables communication between mobile networks and conventional or internet-based phone systems for voice and occasionally S... https://www.gsmgateway.in/what-is-gsm-gateway.html