ignal Processor. There are multiple versions-PVDM, PVDM2, and PVDM3, for example. PVDMs are Digital Signal Chapter 30: VolP Processors (DSP). DSPs are specialized computers on a chip that convert signals from one format to another, compress or decompress a signal, or in some way alter or analyze a signal. They may convert from analog to digital or digital to analog like a DAC, but they may also convert from one CODEC to another. You may not need a PVDM if you're building the environment I've built in this chapter. Cisco IP phones have DSPs built into them, SO they do the conversion from analog to digital and back again. If you're using a network for long-haul toll bypass (using the network instead of the phone company), you may need PVDMs to convert to a CODEC with more compression when sending the call across the cloud. Cisco Unified Communications Manager Formerly Cisco Call Manager (CCM), Cisco Unified Communications Manager (CUCM) is the Cisco IP equivalent of a PBX. It was likely renamed because it is capable of much more than just voice calls. CUCM is usually installed on one or more servers (possibly in a cluster) in a central location. There's a good chance you'll hear people call this product Call Manager regardless of what's actually installed. Cisco Unified Communications Manager Express Formerly Call Manager Express (CME), this product is a scaled-down version of CUCM that resides within a Cisco router. CUCM Express (CUCME) is also often used for SRST. CUCME is what we'll be using in this chapter. You'll notice that I use the term CME constantly even though I've got CUCME installed. I refuse to use the term CUCME when CME rolls off the tongue SO well. Cisco Unity Unity is Cisco's Enterprise voicemail application, which encompasses Microsoft Exchange, Active Directory, and domain controllers. Cisco Unity is outside the scope of this book. Cisco Unity Connection Cisco Unity Connection is Cisco's new direction on voicemail; it decouples the entire Microsoft infrastructure used in Cisco Unity. Cisco Unity