S50 - is a PBX of VoIP technology. It has all the functionality that a telephone exchange can have.
IP phones: 50Simultaneous conversations: 25Number of trunks: 50Analog Ports (FXS/FXO/BRI): 8Wireless channels (GSM/3G/4G): 4
Yeastar_S_Series_VoIP_PBX_Datasheet_en.pdf