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. This 6-port AVM Voice Interface Module requires one to six APMs and one voice compression module (VCM3 or VCM6). Each installed voice port is supported by an analog personality module (APM).