1. DSR Mobile Number Portability User Guide
  2. vSTP G-Flex Feature
  3. G-Flex MAP Layer Routing (G-Flex MLR) Feature
  4. G-Flex MAP Layer Routing

6.3.1 G-Flex MAP Layer Routing

The vSTP G-Flex feature can perform GDB subscriber number lookup based either on a subscriber’s E.164 MSISDN number, or the subscriber’s E.212 IMSI number. In some GSM networks, MSCs use an E.214 MGT (Mobile Global Title) number for routing between networks. G-Flex cannot perform database lookup directly with an E.214 MGT number, but it can convert the E.214 MGT into a E.212 IMSI number, and thus correctly process the message. In an ITU network, when a visited network entity (VLR, GGSN, SGSN, or GMLC) needs to contact a home network entity ( AuC or HLR) given only the IMSI of a subscriber, it will convert the E.212 IMSI into an E.214 MGT. This process applies only to the first message of a dialogue. Subsequent messages of that same dialogue will be routed using E.164 numbers.

When the SCCP CdPA is truncated by the MSC in a message that is received for G-Flex service, G-Flex needs to use the subscriber number from the MAP layer for routing.

The G-Flex MLR feature supports G-Flex routing for messages based on the MAP-layer IMSI and MSISDN parameters that does not involve checking the format of the CdPA , though the messages contain SCCP Called Party Address (CdPA) parameters in ITU E.214 format. The CdPA should contain an E.214 number, but its format and content have no bearing on the G-Flex MLR function.

G-Flex MLR processes messages with the MAP operations shown in the following table:

Table 6-5 MAP Operations Processed by G-Flex MLR

MAP Operation Name Processing
updateLocation G-Flex MLR processes messages with MAP operations that commonly encode the SCCP CdPA GTA in the E.214 format (MGT) where trailing IMSI digits may be truncated from the MGT, and that always include IMSI in the MAP layer.
updateGprsLocation
sendParameters
sendAuthenicationInfo
registerSS
activateSS
deactivateSS
interrogateSS
authenticationFailureReport
restoreData
readyForSM
purgeMS
processUnstructuredSS-Request G-Flex MLR processes messages with MAP operations that include either an IMSI or an MSISDN in the TCAP component.
sendRoutingInfoForLCS
AnyTimeInterrogation G-Flex MLR processes messages with the AnyTimeInterrogation (ATI) operation, using the MSISDN from the MAP layer of the ATI message for conditioning and GDB look up. The MSISDN is converted to International format for GDB searching based on the Nature of Address Indicator in the MAP MSISDN parameter. No HomeRN deletion is required.

The Application Context Name and version supported by G-Flex MLR are shown in the following table:

Table 6-6 MAP Protocol Versions Supported by G-Flex MLR

MAP Operation MAP Operation Name Application Context Name and Version Supported IMSI from Component or Dialogue Portion of TCAP Lookup for MSISDN if IMSI is Missing MSISDN from Component or Dialogue Portion of TCAP
Location Update (2) updateLocation networkLocUpContext-v3

application-context-name value of 0.4.0.0.1.0.1.3

 Component No NA
networkLocUpContext-v2

application-context-name value of 0.4.0.0.1.0.1.2.
networkLocUpContext-v1
Send Parameters (9) sendParameters infoRetrievalContext-v1 Component No NA
Update GPRS Location (23) updateGprsLocation gprsLocationUpdateContext-v3

application-context-name value of 0.4.0.0.1.0.32.

 Component No NA
Send Authentication Information (56) sendAuthenticationInfo infoRetrievalContext-v3

application-context-name value of 0.4.0.0.1.0.14.3.

 Component No NA
infoRetrievalContext-v2

application-context-name value of 0.4.0.0.1.0.14.2.
AnyTime Interrogation (71) AnyTimeInterrogation anyTimeInfoEnquiryContext-v3

application-context-name value of 0.4.0.0.1.0.29.3.

 NA Yes (MSISDN is only looked up) Component
Register Supplementary Service (10) registerSS networkFunctionalSsContext-v2 Dialogue No NA
Activate Supplementary Service (12) activateSS networkFunctionalSsContext-v2 Dialogue No NA
Deactivate Supplementary Service (13) deactivateSS networkFunctionalSsContext-v2 Dialogue No NA
Interrogate Supplementary Service (14) interrogateSS networkFunctionalSsContext-v2 Dialogue No NA
Authentication Failure Report (15) authenticationFailureReport authenticationFailureReportContext-v3 Component No NA
Restore Data (57) restoreData networkLocUpContext-v3

networkLocUpContext-v2

 Component No NA
Process Unstructured SS Request (59) processUnstructuredSS-Request networkUnstructuredSsContext-v2 Dialogue Yes Dialogue
Ready For Short Message (66) readyForSM mwdMngtContext-v3

mwdMngtContext-v2

 Component No NA
Purge Mobile Subscriber (67) purgeMS msPurgingContext-v3

msPurgingContext-v2

 Component No NA
Send Routing Information for Location Service (85) sendRoutingInfoForLCS locationSvcGatewayContext-v3 Component Yes Component
G-Flex MLR processes messages with the following MAP operations commonly encode the SCCP CdPA GTA in the E.214 format (MGT) where trailing IMSI digits may be truncated from the MGT, and these messages always include IMSI in the MAP layer.
  • MAP Update_Location
  • Update_GPRS_Location
  • Send_Parameters
  • MAP Send_Authentication_Information

G-Flex MLR also processes messages with the AnyTimeInterrogation (ATI) operation, using the MSISDN from the MAP layer of the ATI message for conditioning and GDB look up. The MSISDN is converted to International format for GDB searching based on the Nature of Address Indicator in the MAP MSISDN parameter. No HomeRN deletion is required.

For the following MAP Operations, G-Flex MLR uses the GSMOPTS GFLEXMAPLAYERRTG configuration option value to determine whether to use the IMSI or MSISDN to obtain subscriber digits from the MAP layer when performing GDB lookup:
  • updateLocation
  • updateGprsLocation
  • sendParameters
  • sendAuthenicationInfo
  • AnyTimeInterrogation
The GFLEXMAPLAYERRTG option can have the following values:

  • NONE - The G-Flex MLR function is not performed for a message that contains an updateLocation, sendParameters, sendAuthenticationInfo, updateGprsLocation, or AnyTimeInterrogation operation code. Normal G-Flex processing is applied to the message. The IMSI or MSISDN is taken from the SCCP CdPA parameter for TC-BEGIN messages.

  • IMSI - The G-Flex MLR function uses the IMSI for the GDB lookup, for the updateLocation, sendParameters, sendAuthenticationInfo, and updateGprsLocation operations.

  • MSISDN - The G-Flex MLR function uses the MSISDN for the GDB lookup, for the AnyTimeInterrogation operation.

  • All - The G-Flex MLR function uses the IMSI or the MSISDN for the GDB lookup, based on the operation code of the message. If the message contains an updateLocation, sendParameters, sendAuthenticationInfo, or updateGprsLocation operation code, the G-Flex MLR function uses the IMSI parameter. If the message contains an AnyTimeInterrogation operation code, the G-Flex MLR function uses the MSISDN parameter.

For the operations shown in Table 6-7, G-Flex MLR uses the GSMOPTS MAPLYRRTGON configuration option to turn on processing of each specified operation or all operations, and the MAPLYRRTGOFF configuration option to turn off processing of each specified operation or all operations. The values are specified in a comma-separated list for the option in the chg-gsmopts command. One or both options can be specified in one command, but the same value cannot be specified in both options in the same command. When ALL is specified for one option, the other option cannot be specified in the same command.

Table 6-7 GSMOPTS Configuration Options MAPLYRRTGON and MAPLYRRTGOFF

Operation Name Configuration Option Value
registerSS regss
activateSS actss
deactivateSS dactss
interrogateSS intross
authenticationFailureReport authfailrpt
restoreData rstdata
processUnstructuredSS-Request procunstrqt
readyForSM rdyforsm
purgeMS purgmobss
sendRoutingInfoForLCS sriloc
All 10 operations listed in this table all
"Normal" G-Flex processing is performed using the SCCP CdPA when:
  • The G-Flex MLR feature is not turned on.
  • The received message does not include an operation of interest.
  • The operation does not contain an IMSI parameter.
  • The operation does not contain an MSISDN parameter. No measurement is generated.
  • The G-Flex MLR feature encounters a supported operation code that contains an invalid ACN.
The G-Flex MLR feature applies only when:
  • The G-Flex MLR feature is enabled and turned on.
  • An incoming MSU contains and SCCP UDT message type code or XUDT non-segmented message type code.
  • The message contains a TCAP Message Type of Begin (in the MAP layer information of only the first TCAP component of the message).
  • The TCAP component is Invoke.
  • The GSMOPTS GFLEXMAPLAYERRTG configuration option is not NONE.
  • For the message processing controlled by the GSMOPTS GFLEXMAPLAYERRTG configuration option, the option is not NONE.
  • For the message processing controlled by the MAPLYRRTGON option, the option must be set for the operation code in the incoming message, and

    • SCCP CdPA NP=E.214 if CdPA GTI=4 and NP is present.

    • The length of the MCC+MNC (Mobile Country Code + Mobile Network Code) in the resulting E.212 IMSI number must be greater than the length of the CC+NDC (Country Code+Network Destination Code) in the E214 MGT number that is converted to the E212 IMSI number. The maximum length of the SCCP CdPA is 15 digits.

      If the MCC+MNC length is greater than the CC+NDC length and CdPA is 15 digits, then after E.214 MGT to E.212 IMSI conversion, the resulting number of digits is greater than 15. The last digits may be truncated; in this case IMSI digits can be taken from the MAP layer.

    • SCCP CdPA GTI=2
      • The SCCP CdPA GTA length is not checked because the SCCP CdPA Encoding Scheme (ODD or EVEN) is not known in this case, and there might be filler digits ('0') that make the length determination uncertain.

      or

      The CdPA GTI=4 and the SCCP CdPA length is 15 digits.
      • If the length of the SCCP CdPA GTA is 16 digits and the last digit is a stop digit ('0xF'), the stop digit is treated as a filler digit and the CdPA GTA length is considered to be 15 digits.
      • If the CdPA GTI=4, the SCCP CdPA GTA is 8 bytes, and the Encoding Scheme is not BCD ODD (1) or BCD EVEN (2), the Encoding Scheme is assumed to be BCD EVEN (2).
The G-Flex MLR measurements are generated to indicate the following errors in the IMSI and MSISDN parameter in a message. Normal G-Flex processing is applied to the message.
  • Missing IMSI (a measurement is not generated for a missing MSISDN)
  • Decoding errors such as an IMSI parameter value that does not have at least 5 digits and no more than 15 digits, or an MSISDN parameter value that does not have at least 1 digit and no more than 15 digits
  • MSISDN digits with the NAI set to Subscriber or National and the STPOPTS Default Country Code (DEFCC) or Default Network Destination Code (DEFNDC) configuration option is not set appropriately
  • Invalid TCAP component

G-Flex MLR affects only the selection of digits for GDB lookup. All other processing is the same as G-Flex. No changes are made to the MAP layer of the outgoing message; the SCCP layer may be changed per the provisioned Network Entity parameters in the EPAP (such as Digit Action).