Yeastar SO 1-Port FXS & 1-Port FXO Module for S-Series VoIP PBX - Ports: 1x FXO RJ11 Port + 1x FXS RJ11 FXO Port - FXO Ring Frequency Detection: 15 ~ 50Hz - FXS Ring Frequency: 25Hz - Termination: PSNT Lines and Analog Telephone/Fax Machine - Terminating Impedance: 600 Ohm - Ring Voltage: 85V -…