The OpenVox E1/T1/PRI VoIP Gateway is a cost-effective, open-source Asterisk-based solution designed to connect traditional telephone systems (PSTN) to IP networks. It's particularly aimed at operators and call centers looking to integrate their legacy PBX systems with VoIP environments. https://www.callcentersolution.in/products/product-details/100/openvox-dgw-l301-pri-voip-gateway