Overview

ISDN extends the signaling network already in use by the telephone companies out to the subscriber. This means subscribers can send control information from their PBXs to other PBXs at a remote office, using the ISDN. The ISDN messages are translated at the local telephone company office into SS7 messages and are routed over the SS7 network to the destination exchange, where they are converted back into ISDN messages and forwarded to the destination PBX.

There are many other advantages to having access to signaling information. Consider this scenario. A large corporation sells its products through a mail order catalog. It advertises an 800 number, which routes to its ordering center. When a call is received, the ISDN D channel provides the calling party s telephone number. This is then sent to a database residing in an adjunct processor.

The database looks up the telephone number and finds a record providing the calling party s name, address, and past ordering history (if that person has called in before). The operator then receives the call, along with the database information (displayed on the terminal screen). The operator can now provide more personal service and needs to only verify the address and credit card information because that information is already provided by the database.

The same company can also use ISDN to dynamically route callers based on operator availability. Callers can be routed to customized recordings, voice response systems, and other automated systems, reducing the number of calls requiring a live operator. If...