Overview

The ability of a caller to go off-hook in a telephone world, dial digits, and then miraculously talk to someone anywhere in the world is still a mystique to many. The network's capability to set the call up almost instantly and then tear it down just as fast is what really carries the mystique. How can the network figure out where to send the call, get the connection, and ring the phone on the other end so quickly? All of this happens in under a second, and the user is oblivious as to the intricacies of what occurs. What happens behind the scenes constitutes the backbone of the signaling systems. The networks are now dependent on the capability of handling subsecond call set-ups and teardowns.

Several signaling systems have been introduced to the telecommunications networks. The current one in use is called SS7 in North America. In the rest of the world, this is referred to as CCITT Common Channel Interoffice Signaling System 7 (CCS7 for short). Although the names are different, the functions and the purposes of the two systems are the same. As always, the North Americans do things one way, and the rest of the world does things a different way. This is an age-old problem, but one that we have learned to deal with and adjust to.

The essence of the signaling system boils down to many different factors, but one of the most significant reasons the carriers employ these systems is to save...