A new concept being introduced with the Cisco 2821 integrated services router and above is the Extension Voice Module (EVM) and Extension Voice Module slot. The EVM is a dedicated slot intended for voice support only. The EVM card (with expansion modules) supports high-density analog FXS, FXO,DID and BRI ports allow a Cisco 2821 and Cisco 2851 to scale to meet the IP Telephony needs of bigger branch offices where more analog ports are needed then where traditionally supported on prior generations of routers.