 Connection is a Linux appliance running an Informix database that supports Unified and Integra- ted Messaging. In the latest versions, it also supports single-inbox for Exchange environments, where all of your messages, regardless of format (voice or text) are stored in the same inbox. This product is not covered in this book. Cisco Unity Express Cisco Unity Express (CUE) is a scaled-down version of Unity for use within Cisco voice-enabled routers. CUE resides on a small computer built into network mod- ules or AIM daughter cards. These modules vary in capacity for use in different- size environments. While I will reference CUE in this chapter, its configuration will not be covered. We will, however, look at how to connect to a properly configured CUE from within CME, er, CUCME. How VolP Works Common Issues with VolP When dealing with digitized voice, you'll encounter some common issues. These issues are not confined to VoIP, but you'l likely hear about them when working with other VoIP engineers. Let's take a look at them. Latency Latency is the amount of time it takes for packets to traverse the network. In VoIP, that translates roughly to ping times. The thing to remember is that the magic number for roundtrip VoIP is 300 ms. The ITU-T G.114 spec recommends no more than 150 ms latency one way for voice calls (hence 300 ms roundtrip). In reality, the average person will start to complain around 250 ms. Since I'm a control-freak pain in the ass with a low tolerance for latency, even 180 ms roundtrip latency annoys me. Ever notice when you're talking to someone, cell phone to cell phone, that you tend to both start talking at the same time? That's latency in real life. Consider a modern digital cell phone call: phone A converts your call to digital, compresses it, and then sends the signal to a local radio tower. That tower receives the call and sends it over one or more land-based networks (possibly between multiple carriers) to the tower nearest to phone B. That tower then transmits the signal phone B, which u