Message Forwarding

GFRF Forwarding Message: MTP Portion

G-Flex modifies the MTP routing label to include the HLR PC as the DPC and the vSTP true PC as the OPC. G-Flex modifies the MTP Level 2 length based on the size of the forwarding message. The following tables lists the fields modified by G-Flex Relay:

Table 6-3 G-Flex Relay Forwarding Message: MTP Portion

Fields	Values
MTP Level 2 length	Number of octets in response MSU starting from MTP3 SIO field. If number of octets is greater than 63, Level 2 length is set to 63
MTP Level 3 DPC	Point code obtained from the HLR GT information in GDB
MTP Level 3 OPC	vSTP true PC

G-Flex Relay Forwarding Message: SCCP Portion

The following functions are performed for the SCCP portion of the message:

Replacing the CdPA GTAI digits with the HLR entity number

When an MSISDN or IMSI number is found in the GDB and the Replace GT flag is set for this entry, G-Flex Relay replaces the CdPA GTAI digits with the provisioned HLR entity number. G-Flex also modifies the numbering plan (E.164), nature of address (international), and encoding scheme to match the HLR entity number.

G-Flex Relay does not replace the Global Title Indicator format (GTI) element of the GT.

Replacing of SSN in the CdPA

When the HLR translation data includes a SSN, G-Flex Relay replaces the SSN in the called party address of the message with the new SSN. If the SSN is not present in the incoming message, then G-Flex Relay updates the Subsystem Number Indicator and includes the new SSN in the Called Party Address of the message before it forwards the message to the next node.

Inclusion of OPC in the CgPA

When the routing indicator of the calling party address is set to Route-on-SSN, and no SPC is present in it, the OPC from the received message is taken and inserted into the CgPA before the message is forwarded to the next node.

Deleting the CdPA GT Digits

When G-Flex performs Final-GTT, the Routing Indicator of the Called Party Address is set to Route-on-SSN. G-Flex provides an option to delete the Global Title present in the Called Party Address. If the Delete GT option is set, G-Flex modifies the GTI to zero and deletes the GT information from the SCCP CdPA before the message is forwarded to the end node. The following table summarizes the possible changes by G-Flex Relay to the SCCP fields:

Table 6-4 G-Flex Relay Forwarding Message: SCCP Portion

Field	Value
SCCP CdPA Length	New CdPA length after the possible modifications
SCCP CdPA Routing indicator	Routing Indicator obtained from the GDB. (GT or DPCSSN)
SCCP CdPA Global Title Indicator	Same as incoming message or zero
SCCP CdPA Subsystem Number Indicator	Same as incoming message or replaced/inserted with the subsystem number indicator based on the existence of the SSN provisioned in the HLR translation
SCCP CdPA SSN	Same as incoming message or replaced/inserted with the SSN provisioned in the HLR translation
SCCP CdPA GT	Same as incoming message or replaced or deleted with HLR entity address provisioned in the GDB
SCCP CgPA Length	New CgPA length after the possible modifications
SCCP CgPA Point Code Indicator	Same as incoming message or if CgPA RI is Route-on-SSN and PCI is not 1, then set PCI to 1
SCCP CgPA SPC	If the CgPA RI is Route-on-SSN and no point code is present in the CgPA SPC, then the OPC is included as the SPC (Secondary Point Code)
SCCP CdPA Subsystem Number Indicator	Same as incoming message or replaced/inserted with the Subsystem Number indicator based on the existence of the SSN provisioned in the HLR translation

Error Handling

The purpose of the Error Handling is to discard or return messages that encounter routing and database failures and cannot be delivered to the HLR. When G-Flex Relay is unable to transfer a message and Return on Error is set, then G-Flex Relay follows the same error handling procedures used by GTT. The DATA field of the UDT message and the reason cause for return are included in UDTS message.

G-Flex Relay follows the same error handling procedures as GTT for the following error cases:

• Routing failures

• Network congestion

Forwarding message after replace GT and/or Insertion of OPC or SSN is greater than the CCS7 message limit (272 bytes).

An exception to GTT error handling is when the G-Flex Relay GDB entry cannot be found. In this case, it is not considered an error and the G-Flex Relay capability will forward the message to GTT processing.