The X400M FXO module allows the TDM800P card or 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.

Trunk-FXO (Foreign Exchange Office). FXO is an interface that connects to a trunk line, like the one from your service provider. It receives ringing voltage and battery from FXS devices. FXO interfaces are used to connect your PBX to the PSTN. One FXO channel is required for each line your receive from your telco.