To support analog voice circuits, a Cisco MC3810 series concentrator must be equipped with an analog voice module (AVM). In its optional analog voice configuration, a Cisco MC3810 series concentrator can have up to six analog voice ports.By installing specific signaling modules known as analog personality modules (APMs), you can equip the analog voice ports for the following signaling types in various combinations: FXS, FXO, and E&M.