rvice offered. Signaling: In-Band Versus Out-Of-Band Network signaling is used to control the operations in a carrier's network and to establish connections between communication endpoints. The two categories of network signaling are in-band and out-of-band The most noticeable difference between the two is the fast call setup times that out-of-band signaling delivers-often less than one second, compared to the 30 seconds (or r more) setup time required to establish an in-band signaled connection. Out-of-band signaling involves the separation of network signaling from customer data. This arrangement delivers the entire bandwidth of a digital channel for use by the customer. When signaling is separated from the transmission path, the result is clear channels, which are, by definition, 64 Kbps wide. In-band signaling is an older method of establishing network connections. It requires that a customer relinquish some channel bandwidth to the carrier, who uses it for signaling. This technique of deriving bandwidth for network overhead is known as Video Communications: The Whole Picture bit-robbing. A bit-robbed 64 Kbps line will only carry 56 Kbps of customer data. In-band signaling steals valuable bandwidth from the customer's channel and is inefficient. Call set-up requests are routed progressively, from switching center to another, using the same circuit that the call will travel over after the connection is established. The method is slow and inefficient because each switching point introduces processing delays. A call could travel nearly all the way to its destination only to be blocked at a busy CO. During the time it took to reach its point of failure, the doomed call will have tied up circuits that other calls could have used. Inside their own networks, carriers use out-of-band signaling methods to establish connections. Requests for call set-up and teardown are conveyed separately from the call itself, as are special messages that indicate caller-ID, class of service status, and other customer-specific data. T