Global Title Translation Feature

The Global Title Translation (GTT) feature is designed for the signaling connection control part (SCCP) of the SS7 protocol. The EAGLE uses this feature to determine to which service database to send the query message when a Message Signaling Unit (MSU) enters the EAGLE and more information is needed to route the MSU.

If an MSU enters the EAGLE and more information is needed to route the MSU, the SCCP of the SS7 protocol sends a query to a service database to obtain the information. The EAGLE uses the GTT feature for the SCCP to determine which service database to send the query messages to. These service databases are also used to verify calling card numbers and credit card numbers. The service databases are identified in the SS7 network by a point code and a subsystem number.

The GTT feature uses global title address (GTA) information to determine the destination of the MSU. The translation type (TT) indicates which global title translation table is used to determine the routing to a particular service database. Each global title translation 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 routing indicator determines if further global title translations are required. GTA and TT are contained in the called party address (CDPA) field of the MSU.

The global title translation feature changes the destination point code and the origination point code in the routing label. The global title information is not altered. The routing label is changed to indicate the new destination point code retrieved from the global title translation and the origination point code is set to the EAGLE’s point code.

Depending on how the global title translation data is configured, the routing indicator, the subsystem number, or the translation type in the called party address may also be changed by the global title translation feature. The gray shaded areas in Figure 2-1 show the message fields affected by global title translation.

Figure 2-1 ANSI and ITU MSU Fields affected by the Global Title Translation Feature

The GTT feature allows global title translation on global title addresses of fixed length. There are three optional add-on features that enhance the functionality of the global title translation feature:

• The Variable-length Global Title Translation feature (VGTT) feature allows global title translation on global title addresses of varying length. For more information on this feature, refer to the Variable-length Global Title Translation Feature section.
• The Advanced GT Modification feature allows the EAGLE to modify other fields of an MSU in addition to the translation type when the MSU requires further global title translation and the translation type is to be replaced. For more information about this feature, refer to the Advanced GT Modification Feature section.
• The ANSI/ITU SCCP Conversion Feature converts SCCP messages between the ANSI and ITU formats. For more information about this feature, refer to the ANSI/ITU SCCP Conversion Featuresection.

The EAGLE supports:

• 269,999, 400,000, or 1,000,000 global title translations. The system default is 269,999 global title translations. This quantity can be increased to 400,000 by enabling the feature access key for part number 893-0061-01, or to 1,000,000 by enabling the feature access key for part number 893-0061-10. For more information on enabling these feature access keys, refer to the Enabling the XGTT Table Expansion Feature procedure.
• A maximum of 200,000 global title translations assigned to a translation type.
• 512 translation types, 256 translation types for ANSI MSUs, and 256 translation types for ITU MSUs.
• 1024, 2000, or 3000 remote point codes (mated applications), with up to 10 subsystems at each point code. The system default is 1024 mated applications. This quantity can be increased to 2000 by enabling the feature access key for part number 893-0077-01, or to 3000 by enabling the feature access key for part number 893-0077-10. For more information on enabling these feature access keys, refer to the Enabling the XMAP Table Expansion Feature procedure.

The GTT feature requires one of the following cards:

• Database Services Module (DSM) (Refers to the E5-SM4G or E5-SM8G-B card)
• SLIC card

For more information on these cards, refer to the Adding a Service Module procedure or to Hardware Reference.