SOR During the UE Registration Call Flow

This section describes the SOR during the UE Registration call flow.

SOR During the UE Registration Call Flow
SOR During the UE Registration Call Flow Description

Step

Description

1

UE sends the Registration Request to the VPLMN AMF.

2

The VPLMN AMF executes the registration procedure as defined in subclause 3GPP TS 23.502 [63], section 4.2.2.2.2.

As part of the registration procedure, the VPLMN AMF invokes the Nudm_SDM_Get service operation message to the HPLMN UDM.

This service operation helps in getting the Access and Mobility Subscription data for the UE.

3

The following are the responses from the HPLMN UDM, reciprocating to the Nudm_SDM_Get service operation message:

  • Sending SOR

  • Requesting ACK from the UE

4

When the HPLMN UDM sends the response using the Nudm_SDM_Get service operation to the VPLMN AMF, the following are the next substeps:

  • This response includes the SOR information in the Access and Mobility Subscription data.

    Note

    The Access and Mobility Subscription data type defined as in 3GPP TS 23.502, section 5.2.3.3.1.

  • The HPLMN requests the UE to ACK the successful security check of the received SOR information.

  • The HPLMN requests this ACK with an indication in the Nudm_SDM_Get service operation of SOR information.

5

As part of the registration procedure, the VPLMN AMF invokes the Nudm_SDM_Subscribe service operation to the HPLMN UDM:

  • To subscribe to the subscription data notification changes received in Step 4.

  • To include the notification of SOR updates in the Access and Mobility Subscription data.

6

The VPLMN AMF sends the received SOR information to the UE in Registration Accept.

7

The SOR security check procedure takes place at UE.

8

The UE performs the PLMN selection procedure and ends the procedure, when:

  • The information check fails.

  • Although the UE is configured to receive the SOR information, but it does not receive.

9

UE sends Registration Complete to the serving AMF with an SOR transparent container including the UE ACK:

  • When the UDM requested an ACK from the UE.

  • When the UE verifies the HPLMN SOR information from Step 7.

10

AMF uses the Nudm_SDM_Info service operation to provide the received SOR transparent container to the UDM in Registration Complete:
  • If the HPLMN decides that the UE must ACK with the successful security check for the received SOR information from Step 4, then the verification process begins.

  • If the UDM verifies the ACK provided by UE specified in 3GPP TS 33.501.

11

UE performs the PLMN selection when a high priority PLMN is available.