Yeastar S-Series VoIP PBX provides flexible telephony interfaces combination while allowing for future scalability with unique modular design. Besides the built-in rich SIP capabilities, S-Series lets you decide what types of extensions and physical trunks you need in your telephone system. When your business grows, adding more users and concurrent calls is also possible with S-Series. Yeastar S2 Module is a module with 2 FXS ports to terminate two analog telephone. S2 Module 2FXS is compatible with MyPBX series and S-Series PBX. The S2 is a module with 2 FXS ports to terminate two analog telephones. It can be used in PBX SOHO, MyPBX Standard, MyPBX Pro, MyPBX E1, MyPBX E1 Plus, MyPBX Enterprise, and TDM800 Card