Multi-SIM VoIP GSM/3G/4G Gateway — an innovative telecom solution combining multi-SIM and VoIP gateway functionalities in one. It features 4 SIM slots per channel, with scalable configurations such as 8 , 16 , or 32 channels supporting up to 128 SIMs, and allows hot-swappable SIM management for easy maintenance. https://www.gsmgateway.in/dinstar/GSM-3G-4G-VoIP-Gateway/Multi-SIM-VoIP-Gateway.html