7.2.2 Retrieval of routeing information procedure
23.1193GPPGateway Location Register (GLR)Release 17Stage 2TS
In 3G TS 23.018 [4](Basic Call Handling) specification, the description for the basic call handling about MO and MT is stated.
Only the retrieval of routeing information for an MT call is related with the GLR.
Therefore, this specification states the retrieval of routeing information for an MT call.
7.2.2.1 Information flow for retrieval of routeing information for an MT call
The information flow for retrieval of routeing information for an MT call is shown in figure 7.2/12. Solid lines show ISUP signalling between the originating exchange and GMSCB, and between GMSCB and VMSCB; signalling over the MAP interfaces between GMSCB and HLRB and between HLRB and VLRB is shown by chain lines.
Figure 7.2/12: Information flow for retrieval of routeing information for a basic mobile terminated call
When GMSCB receives an IAM, it analyses the called party address. If GMSCB can derive an HLR address from the B party address, it sends a request for routeing information (SRI) to HLRB. HLRB sends a request for a roaming number (PRN) to VLRB via GLRB. VLRB returns the roaming number in the PRN ack via GLR, and HLRB relays the roaming number to GMSCB in the SRI ack. GMSCB constructs an IAM using the roaming number, and sends it to VMSCB.
If the VLRB supports the Super-Charger features, when the VLRB receives a request for a roaming number (PRN) and has no subscriber data for the user, it checks whether the subscriber data record was removed by the Super-Charger database management function or not. (See 3G TS 23.116 [9]) If the subscriber data was removed by the Super-Charger feature, the VLRB shall return the cause information set to Purged MS to the GLR by sending PRN negative response. When the GLR receives this information, it deletes the subscriber data for the user and relays the message to the HLR.
7.2.2.2 Functional requirements of network entities
The text in this clause is a supplement to the definition in the SDL diagrams; it does not duplicate the information in the SDL diagrams.
The entities described in this clause interwork with other entities over the D interfaces, used to interwork between the VLR & HLR.
The protocol used over the D interfaces is MAP, which is specified in 3G TS 29.002 [10].
For the purposes of this specification, the protocol used over telephony signalling interfaces is ISUP, which is specified in ETS 300 356‑1 [27]; other telephony signalling systems may be used instead.
The SDL diagrams in this clause show the handling for a number of optional features and services. If the handling consists only of a call to a procedure specific to the feature or service, the procedure call is omitted if the entity does not support an optional feature or service. If the handling consists of more than a call to a procedure specific to the feature or service, the text associated with each SDL diagram specifies the handling that applies if the entity does not support an optional feature or service.
7.2.2.2.1 Functional requirements of GLR
7.2.2.2.1.1 Process PRN_GLR
Figure 7.2/13 shows SDL chart for Process PRN_GLR.
Sheet1: the GLR receives a PRN message from the HLR.
Sheet1: after the GLR transfers the VLR Number, the GLR relays a PRN message to the VLR.
Sheet1: the GLR waits a PRN response and receives a PRN ack message or a PRN negative response message from the VLR.
Sheet1: after the GLR transfers the HLR Number, the GLR relays a PRN ack message or a PRN negative response message to the HLR.
Figure 7.2/14 shows SDL chart for Procedure Super_Charged_PRN_Error_GLR.
Figure7.2/13: Process PRN_GLR
Figure7.2/14: Procedure Super_Charged_PRN_Error_GLR
7.2.2.2.1.2 Process PSI_GLR
Figure 7.2/15 shows SDL chart for Process PSI_GLR.
Sheet1: the GLR receives a PSI message from the HLR.
Sheet1: after the GLR transfers the VLR Number, the GLR relays a PSI message to the VLR.
Sheet1: the GLR waits a PSI response and receives a PSI ack message or a PSI negative response message from the VLR.
Sheet1: after the GLR transfers the HLR Number, the GLR relays a PSI ack message or a PSI negative response message to the HLR.
Figure7.2/15: Process PSI_GLR
7.2.2.3 Contents of messages (HLR-GLR, GLR-VLR)
There is no different between the contents of the following messages sent between HLR and VLR and the contents of the following messages sent between HLR and GLR, GLR and VLR. The same contents are sent from the HLR to VLR via the GLR. See 3G TS 23.018 [4].
– Provide Roaming Number.
– Provide Roaming Number ack.
– Provide Roaming Number negative response.
– Provide Subscriber Info.
– Provide Subscriber Info ack.
– Provide Subscriber Info negative response.