Digium X400M - Quad Channel Trunk (FXO) Module
The X400M FXO module allows the TDM2400P card to terminate four analog telephone lines (POTS) per module.
Because of the modular design, a user can activate additional ports at any time with more S400M or X400M daughter cards. The X400M module passes all the call features any standard analog telephone line will support. Worldwide certifications are pending.