2.4 Global Title Translation

The Global Title Translation (GTT) feature is designed for the Signaling Connection Control Part (SCCP) of the SS7 protocol.

The GTT feature uses Global Title Address (GTA) information to determine the destination of the MSU. The Translation Type (TT) indicates which GTT table is used to determine the routing to a particular service database. Each GTT table includes the Point Code (PC) of the node containing the service database, the SubSystem Number (SSN) identifying the service database on that node, and a Routing Indicator (RI). The RI determines if further GTTs are required. GTA and TT are contained in the Called Party Address (CdPA) field of the MSU.

The GTT feature changes the destination PC and the origination PC in the routing label. The GTA information is not altered.

Depending on how the GTT data is configured, the GTT may also change the RI, SSN, or the TT in the CdPA. The gray shaded areas in the following tables show the message fields affected by GTT.

Figure 2-2 ANSI MSU (ANSI Message Signal Unit)

Figure 2-3 ITU-I MSU (ITU International Message Signal Unit)

Figure 2-4 14-Bit ITU-N MSU (14-Bit ITU National Message Signal Unit)

Figure 2-5 24-Bit ITU-N MSU (24-Bit ITU National Message Signal Unit)