Cisco Fourth-Generation 64-Channel High-Density Packet Voice Digital Signal Processor Module. This PVDM4 modules are supported on the Cisco 4451-X platform. You can plug them directly into the single slot on the router motherboard or onto the network interface module (NIM) that supports T1/E1 ports. Enhanced DSP architecture accommodates a packet-processing engine optimized for rich-media voice applications, while concurrently supporting the time-division multiplexing IP (TDM-IP) voice framework. A PVDM4 module plugged onto the motherboard delivers IP-based voice services such as conferencing, media optimization, and transcoding.