Yeastar's S20, S-Series VoIP PBX is designed with small and medium sized enterprises in mind and supports up to 20 users. Yeastar's S-Series delivers impressive cost savings, productivity and efficiency improvements, while delivering power, performance, quality and peace of mind.The S-Series features comprehensive auto provisioning, advanced plug and play capability, as well as an intuitive Metro UI driven by point-and-click configuration, accessible from any location. It works with SIP/IAX2, PSTN lines, ISDN BRI, E1/T1/PRI, and GSM/CDMA/3G.*NOTE: Modules not included.Specifications Max Analog Ports: 4Max BRI Ports: 4Max Cellular Ports: 1Max Concurrent Calls: 10Max Users: 20Mounting: DesktopOperating Temperature: 0°C to 40°Storage: TF Card (External)T1/E1/J1 Ports: NoneUSB Port: NoneVoIP Trunks: 20Dimensions: 160 x 160 x 30mmWeight: 0.3kg