22.6 Interrogation procedure

29.0023GPPMobile Application Part (MAP) specificationRelease 17TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

22.6.1 General

The interrogation procedure is used to retrieve information related to a supplementary service from the VLR or the HLR. It is the VLR which decides whether an interrogation request should be forwarded to the HLR or not. Some non-supplementary service related services may be invoked as a result of the procedure, as described in the clauses below.

The interrogation procedure is shown in figure 22.6.1/1.

The following services may be used:

MAP_PROCESS_ACCESS_REQUEST (see clauses 8 and 25);

MAP_TRACE_SUBSCRIBER_ACTIVITY (see clauses 9 and 25);

MAP_PROVIDE_IMSI (see clauses 8 and 25);

MAP_FORWARD_NEW_TMSI (see clauses 8 and 25);

MAP_AUTHENTICATE (see clauses 8 and 25);

MAP_SET_CIPHERING_MODE (see clauses 8 and 25);

MAP_CHECK_IMEI (see clauses 8 and 25);

MAP_READY_FOR_SM (see clauses 12 and 25);

The following service is certainly used:

MAP_INTERROGATE_SS (defined in clause 11).

1) A_CM_SERV_REQ (Note 1)

2) MAP_PROCESS_ACCESS_REQUEST (Note 2)

3) A_INTERROGATE_SS (Note 1)

4) MAP_INTERROGATE_SS_req/ind

5) MAP_INTERROGATE_SS_req/ind

6) MAP_INTERROGATE_SS_rsp/cnf

7) MAP_INTERROGATE_SS_rsp/cnf

8) A_INTERROGATE_SS ack (Note 1)

NOTE 1: For details of the procedure on the radio path, see 3GPP TS 24.008 [35], 3GPP TS 24.010 [36], 3GPP TS 24.08x and 3GPP TS 24.09x. Services shown in dotted lines indicate the trigger provided by the signalling on the radio path, and the signalling triggered on the radio path.

NOTE 2: For details of the Process Access Request procedure, refer to clause 25.4 in the present document.

NOTE 3: Services printed in italics are optional.

Figure 22.6.1/1: Message flow for supplementary service interrogation

22.6.2 Procedure in the MSC

The MSC procedures for interrogation are identical to those specified for registration in clause 22.2.2. The text and diagrams in clause 22.2.2 apply with all references to registration changed to interrogation.

22.6.3 Procedures in the VLR

The MAP process invokes macros not defined in this clause; the definitions of these macros can be found as follows:

Receive_Open_Ind see clause 25.1.1;

Receive_Open_Cnf see clause 25.1.2;

Check_Confirmation see clause 25.2.2;

Process_Access_Request_VLR see clause 25.4.2.

The interrogation is answered either by the VLR or by the HLR, depending on the service interrogated.

1) Interrogation to be handled by the VLR

The supplementary service request shall be processed according to 3GPP TS 23.011 [22] and the 23.08x and 23.09x-series of technical specifications. This handling may lead to a successful result, a partially successful result or an error being returned.

For call independent SS operations, each message shall contain only a single component. Messages which contain more than one component will be stopped at the air interface (as specified in 3GPP TS 29.011 [59]).

2) Interrogation to be handled by the HLR

If the interrogation is to be handled by the HLR, the MAP process in the VLR transfers the information received in the MAP_INTERROGATE_SS indication to the HLR in the MAP_INTERROGATE_SS request without checking the contents of the service indication. The MAP_OPEN request includes the IMSI of the subscriber as the destination reference and the VLR number as the originating reference.

If the MAP_INTERROGATE_SS confirm is properly formed and contains a result or a user error, the MAP process in the VLR shall transfer the information contained in this primitive to the MSC in the MAP_INTERROGATE_SS response.

The Interrogation process in the VLR is shown in figure 22.6.3/1.

22.6.4 Procedure in the HLR

The MAP process invokes a macro not defined in this clause; the definition of this macro can be found as follows:

Check_Indication see clause 25.2.1.

The HLR acts as follows:

The interrogation is answered either by the VLR or by the HLR, depending on the service interrogated.

1) Interrogation to be handled by the VLR

If the interrogation procedure should have been answered by the VLR, then the HLR assumes that the VLR does not support the interrogated supplementary service, and returns the SS Not Available error to the VLR.

2) Interrogation to be handled by HLR

The supplementary service request shall be processed according to 3GPP TS 23.011 [22] and the 23.08x and 23.09x-series of technical specifications. This handling may lead to either a successful result or an error being returned.

The Interrogation process in the HLR is shown in figure 22.6.4/1.

Figure 22.6.3/1 (sheet 1 of 2): Process Interrogate_SS_VLR

Figure 22.6.3/1 (sheet 2 of 2): Process Interrogate_SS_VLR

Figure 22.6.4/1: Process Interrogate_SS_HLR