The Cisco Packet Voice Digital Signal Processor Modules (PVDMs) enable Cisco 4000 Series Integrated Services Routers (ISRs) to provide rich-media capabilities such as high-density voice connectivity conferencing transcoding media optimization transrating and secure voice for Cisco Unified Communications solutions. These new modules support unprecedented scale while allowing for a smaller solution footprint than ever before.The PVDMs support digital voice connections conferencing universal transcoding and media optimization services:- T1/E1 voice: One of the primary uses of PVDMs is to packetize digital voice into IP packets to enable time-division multiplexing (TDM) digital voice applications.- Conferencing: PVDM modules support ad hoc and meet-me conferencing with various codecs in conjunction with Cisco Unified Communications Manager and Cisco Unified Communications Manager Express.- Universal transcoding: In conjunction with Cisco IOS Software the PVDMs support universal transcoding which allows conversion from any supported codec to any other supported codec.- Transrating: The PVDMs support transrating in which the same codec is repacketized in order to connect dissimilar networks that have different codec packetization periods.- Voice-quality management: The PVDMs perform compression voice-activity detection jitter management and echo cancellation. The echo cancellation offered in the PVDMs has a tail length of 128 milliseconds and complies with ITU-T G.168.- Energy savings: The motherboard PVDMs (PVDM4s) offer multiple power-saving modes including a power-saver mode when the module is not in use. In power-saver mode each PVDM4 can save up to 5 watts of power.The analog voice modules (FXS FXO and E/M) and Basic Rate Interface (BRI) digital voice modules for the 4000 Series ISRs contain built-in nonconfigurable digital signal processors (DSPs) and do not require any additional PVDMs for voice packetization.