GN-VOIP-FXS-4 analog gateway are versatile IP-based voice and fax gateway. For small business, the family office, remote office and branch business provide a low cost, simple operation VoIP solutions. Connected analog phone, fax, PBX with standard voice interface and provide quality voice service. GN-VOIP-FXS-4 VoIP access gateway use standard SIPprotocol and compatible with Leading IMS/NGN platform, IPPBX and SIP servers.