s a CCIF weighting network is referred to as, Federal Standard 1037C is a good place to look. Another excellent source that should be on the bookshelf of anyone in the telecom world is Newton's Telecom Dictionary, by Harry Newton (CMP Books). The meanings of many widely used telecom terms have changed over time. Through regulation over the years, the functions of entities like IXCs and LECs (both defined below) have changed. I will cover the original intended meanings in this text. Telecom Glossary ACD stands for Automatic Call Distributor. An ACD is usually found in a call center, where calls may come in from anywhere, and need to be directed to the next available operator, or queued until one is available. Add/Drop The term Add/Drop is used in telecom to describe the capability of peeling off channels from a circuit and routing them elsewhere. An Add/Drop CSU/DSU has the ability to separate ranges of channels to discrete data ports, thus allow- ing a T1 to be split into two partial T1s. One could be used for voice, and the other for data, or both could be used for either function and routed differently. You can make an Add/Drop device function like a non-Add/Drop device simply by assigning all of the channels to a single data port. However, Add/Drop functionality adds cost to devices, SO it should only be considered if the added functionality is required. Analog and digital Would you like to have some fun? Ask someone in the computer field to define the word "analog." You might be surprised at some of the answers you receive. Analog means, literally, the same. When one item is analogous to another, it is the same as the other item. In the telecom and data worlds, "analog" refers to a signal that is continuous in amplitude and time. Chapter 19: Telecom Nomenclature An analog signal is not composed of discrete values: any small fluctuation of the signal is important. Radio waves are analog, as are power waves. Sound is also analog. When you speak, you create waves of air that hit people's eardrums. The sound wave