This 3-port FXS and 4-port FXO voice and fax expansion module provides on-premises FXS signaling to connect directly to a standard telephone,fax machine,or similar device and supplies ring,voltage,and dial tone. In addition,the FXO ports provide off-premises connection to the central office. FXS signaling support available includes loop-start and ground-start. There is no DID support. In addition,there is no FXO power failover support on the FXO ports.