A GSM Gateway (also known as a GSM VoIP Gateway, Fixed Cellular Terminal (FCT), or SIM Bank) is a hardware device that acts as a bridge between mobile cellular networks (GSM, 3G, 4G/LTE) and traditional landline phone systems (PSTN) or Voice over IP (VoIP) networks. Its primary purpose is to route telephone calls efficiently and cost-effectively between these different networks. https://www.gsmgateway.in/what-is-gsm-gateway.html