Digium Quad Channel Station (FXS) Module
Quad Channel Station (FXS) Module. The S400M FXS module allows the TDM800P card, or TDM2400P card to terminate four analog telephones per module. Because of the modular design, a user can activate additional ports at any time with more S400M daughter cards. The S400M module passes all the call features any standard analog telephone line will support.