Yeastar S2 Module, 2 FXS Ports. Yeastar S2 module is a module with 2 FXS ports to terminate two analog telephone or fax machines. It is compatible with Yeastar S-Series VoIP PBX and P-Series PBX System. Port: 2 RJ11 FXS Ports On-hook Voltage (tip/ring) 48V Supported Model: S412, S20, S50, S100, S300, P550, P560, P570. Off-hook Current: 10 mA Ring Frequency: 25 Hz Terminating Impedance Option: 600 Ohm Ring Load: 840 Ohm Max Length Supported: 1500M Loop Impedance: 2000 Ohm Pulse Dial Speed: 100~135 ms/ 10pps Loop Current: 20 mA Surge Voltage: 1.5KV (10/70uS) Off-hook Voltage: 11V REN Load (1000M): 5REN=1400 Ohm, 3REN=2330 Ohm, 1REN=7000 Ohm, Ring Voltage 85V