Yeastar S20 PBX Business Phone System Barebones No modules

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. With Yeastar S-Series, all the telephony interfaces are modular and customizable, whether it’s FXS, FXO, ISDN BRI, GSM/3G, or E1/T1/PRI. S20 has 2 onboard module slots.