09.023GPPMobile Application Part (MAP) specificationTS

In the subscriber identity procedure the IMSI of the subscriber is retrieved from the HLR. The procedure is shown in figure 20.4/1.

+—–+ +——+ +——+
ª OMC ª ª VLR ª ª HLR ª
ª ª ª ª ª ª
+—–+ +——+ +——+
ª 1.ª ª ß
+ – – – – >ª 2.ª ß
ª +———————>ª ß
ª ª 3. ª ß
ª 4. +<———————ª ß
+< – – – – ª ª ß
ª ª ª ß

1) Identity request

2) MAP_SEND_IMSI

3) MAP_SEND_IMSI_ACK

4) Identity confirm

Figure 20.4/1: The subscriber identity procedure

20.4.1 Subscriber identity procedure in the HLR

Opening of the dialogue is described in the macro Receive_Open_Ind in subclause 25.1, with outcomes:

– procedure termination; or

– dialogue acceptance, with proceeding as below.

When receiving the MAP_SEND_IMSI indication, the HLR will check the parameters and data in the primitive. Data errors are reported as an unexpected data value error or a data missing error depending on the nature of the error.

If the subscriber is known in the HLR, the IMSI is fetched from the database and sent to the VLR. If the MSISDN cannot be identified, unknown subscriber indication is passed to the VLR.

The subscriber identity procedure in the HLR is shown in figure 20.4/2.

Figure 20.4/2: Process Send_IMSI_HLR

20.4.2 Subscriber identity procedure in the VLR

When the IMSI request is received from the OMC, the VLR will send the MAP_SEND_IMSI request to the HLR. The contents of the response is sent to the OMC.

The subscriber identity procedure in the VLR is shown in figure 20.4/3.

Figure 20.4/3: Process Send_IMSI_VLR