ed. Any use is subject to the Terms of Use as given at the website. Telephony Chapter 3 channel. Whereas 24 channels can be transported over a typical T1 facil- ity, DSI allows for as many as 120 conversations to be carried over the same circuit. The format is proprietary and requires the setting aside of a certain amount of bandwidth for overhead. A form of "statistical multiplexing" lies at the heart of DSI's function- ality. The standard T-Carrier is a time-division multiplexed scheme in which channel ownership is assured: A user assigned to channel three will always own channel three, regardless of whether they are actually using the line. In DSI, channels are not owned. Instead, large numbers of users share a "pool" of available channels. When a user starts to talk, the DSI system assigns an available timeslot to that user and notifies the receiving end of the assignment. This system works well when the num- ber of users is large, because statistical probabilities are more accurate and indicative of behavior in larger populations than in smaller ones. There is a downside to DSI, of course, and it comes in several forms. Competitive clipping occurs when more people start to talk than there are available channels, resulting in someone being unable to talk. Con- nection clipping occurs when the receiving end fails to learn what chan- nel a conversation has been assigned within a reasonable amount of time, resulting in signal loss. Two approaches have been created to address these problems. In the case of competitive clipping, the system intentionally "clips" off the front end of the initial word of the second per- son who speaks. This technique is not optimal, but does prevent loss of the conversation and also obviates the problem of clipping out the mid- dle of a conversation, which would be more difficult for the speakers to recover from. The loss of an initial syllable or two can be mentally recon- structed far more easily than sounds in the middle of a sentence. A second technique used to recover from clipp