Overview

The Transaction Capabilities Application Part (TCAP) is designed for non-circuit-related messages. These messages are destined for database entities as well as actual end-office switches. The TCAP protocol provides a means for the reliable transfer of information from one application at a switch location to another application within another network entity. To understand this, it is probably best to look at some of the actual applications and problems that we face in the telephone network today.

The first use of the TCAP protocol was 800 number translation. An 800 number cannot be routed through the telephone network because the area code 800 does not specify any particular exchange. To overcome this problem, the number must be converted into a routable number. This requires a database.

The database for 800 numbers provides a routing number that the local office then can use to route the call through the Public Switched Telephone Network (PSTN). This database usually is centrally located within the service provider s network. It does not make good sense to place this database in too many multiple locations because that would make maintenance of the database more difficult.

The problem with centralized databases is providing access to them. All switches in the network must be able to access the database and retrieve the routing number for the 800 numbers used on their network. To compound the problem, in today s network, all 800 numbers must be routable by all carriers. This means that no matter which telephone company owns ...