AddPac’s four(4)-port FXS3O1 Voice processing module features three(3)-channel FXS Voice interface and one(1)-channel FXO Voice interface in one module for various combination of voice service. When there is a failure on internet connection or on VoIP call service of Gatekeeper, one(1)-port FXO interface on the module maintains call, turning over to PSTN line without reconnecting.
