The motherboard PVDMs are supported on all Cisco 4000 Series ISRs. They can be plugged directly into the single slot on the router motherboard or into the network interface module (NIM) that supports T1/E1 ports. A PVDM4 module plugged into the motherboard delivers IP-based voice services such as conferencing, media optimization, and transcoding only. A PVDM4 module plugged into the T1/E1 NIM would be used for voice T1/E1 connectivity. Any excess channels can be reused toward other IP-based services supported on the motherboard slot. Enhanced DSP architecture accommodates a new packet-processing engine optimized for rich-media voice applications, while concurrently supporting the TDM-IP voice framework. The PVDM enhanced services modules are supported on ISRs that contain an SM-X slot - namely the Cisco 4331, 4351, and 4451 ISRs. The SM-X modules support only IP-based voice services and cannot be used for TDM applications.