1. Diameter Signaling Router Mobile Number Portability User Guide
  2. vSTP G-Flex Feature
  3. G-Flex Relay Function Description

G-Flex Relay Function Description

The G-Flex Relay Function (G-Flex Relay) provides the following enhancements to vSTP GTT:

  • Increased number of translations – The GTT limit is 270,000 total translations. With G-Flex Relay, the number is millions. However, G-Flex Relay translations are only from international MSISDNs and IMSIs to HLRs.

  • Number conditioning – Because the GDB stores MSISDNs and IMSIs as international numbers and does not store MGTs, G-Flex provides the capability to condition incoming numbers to be international MSISDNs or IMSIs for the database look up.

  • Provides discrimination of messages that need its functionality – Because G-Flex is used only for translating to HLRs, it provides a method to identify which messages are processed by G-Flex Relay and which by. GTT. This is provided using a G-Flex Service Selector table that defaults back to the GTT Selector table if a match is not found, and by providing SSN-based discrimination.

  • Variable number of digits – There is no fixed number of digits for MSISDNs or IMSIs. For example, a 12-digit MSISDN can coexist with a 15-digit one. However, the number of digits of the stored numbers must be between 5 and 15.

  • Replacement of GT with entity address – The ability to set the outgoing CdPA GT (NP, NAI, ES, GTAI) to the HLR international entity number is provided.

The following figure shows the basic functioning of SCCP, with the parts for G-Flex in bold:

Figure 6-3 G-Flex in SCCP

G-Flex in SCCP

In order to keep the diagram simple, the only error conditions shown are the no-match cases for G-Flex and GTT selectors and translations. G-Flex has its own error handling for some cases that issues measurements and peg measurements appropriately before letting the MSU fall through to GTT translation. Also, there are error conditions in GTT selection, GTT translation, and message transfer that are handled by GTT error handling.

G-Flex Relay is performed in the following stages.

  1. The message arrives at vSTP Route-on-GT. The vSTP decodes the SCCP portion and uses the data to perform G-Flex selection based on the CdPA GT fields other than the ES and GTAI. The result of this selection provides two pieces of data, identification of the NP and NAI for G-Flex and a G-Flex Service Indicator. The Service Indicator is G-Flex if G-Flex Relay is required. If a G-Flex selector does not match the incoming GT fields, then GTT selection is attempted. It is possible that G-Flex and GTT selectors will not match the incoming GT fields. In this case, GTT error handling is used.

  2. If stage 1 indicates that G-Flex Relay is required and if the message is not a UDTS-generated by the vSTP, the vSTP performs SSN-based discrimination. If the G-Flex service state is ONLINE, then step 3 is performed. Otherwise, G-Flex SCCP Service Re-Route is performed.

  3. The conditioned number is looked up in the GDB.

  4. If the number is found, the translation data for the number is used to alter and route the message.

  5. If G-Flex Relay is not required, or the number is not found in the GDB, the set of GTT translations is used for translation.

unresolvable-reference.html#GUID-B13D2FF1-24B3-406B-A01B-75E2F505B279__24576 lists possible combinations for G-Flex selector and G-Flex data provisioning, and the resulting action of G-Flex Relay.

Table 6-1 G-Flex Relay Data Combinations

G-Flex Selector Matches Incoming GT Number in GDB vSTP Action

No

N/A

GTT used

Yes

No

Fall-through to GTT

Yes

Yes

G-Flex translation

G-Flex Relay is divided into the following subtasks:

  • Conversion of national/local numbers to international numbers

  • Conversion of E.214 MGT to E.212 international IMSI

  • GDB lookup

  • Message forwarding

  • Error handling