1. Roaming Steering
  2. Understanding SoR Functionality and Logic
  3. SoR Logic Process

SoR Logic Process

In order for SoR logic to be triggered, some prerequisite conditions are required. For example, DCA Framework must be installed and activated and SoR must be activated, enabled, and provisioned. See SoR Pre-Configuration Activities.

SoR logic is triggered when a URL message is received. After triggering, SoR:

  1. Confirms the MCC/MNC value of the visited PLMN as included in the visited-PLMN-ID AVP and verifies whether this value is either explicitly or implicitly included in the SoR_Profile table as part of a Visited-MNO. If that is not the case and the Unknown VPLMN configuration parameter is set to reject, go to 2 ; otherwise, go to 3. See Understanding SoR Configuration Options.
  2. Rejects the registration with a ULA message and updates the related counters. The processing of the current message by the SoR application is now finished.
  3. Confirms whether the registration is from a preferred network; if not, go to 4. Otherwise, go to 10.
  4. Determines if any preferred network has not received its pre-configured share yet and if that is the case, go to 6; otherwise, go to 5. For example, all preferred networks have received (at the minimum) their pre-configured share.
  5. Confirm if the Visited-MNO to which the received MCC/MNC belongs has received its pre-configured value; if yes, go to 6 and if not, go to 10.
  6. Selects the subscriber's UDR entry, which is Information about the number of registration attempts by a subscriber that is kept in a UDR database. If the subscriber still does not have an entry or the entry is outdated, for example, no ULR message of this subscriber was rejected at all or for some time, go to 8; otherwise, go to 7.
  7. Confirms if the ULR message was generated from the same MNO as the last successful ULR for this subscriber (based on the subscriber's UDR record). If that is the case, go to 10; otherwise, go to 9.
  8. Rejects the registration with a ULA message and updates the related counters, as well as the subscriber's UDR record. The processing of the current message by the SoR application is now finished.
  9. Confirms if the number of times the subscription messages of this subscriber (from the subscriber's UDR record) were rejected exceeds either the MaximumAttempts value or the MaxNumOfRejectionsPerMNO value, go to 10; otherwise, go to 8.
  10. Accepts the registration and updates the related counters and the subscriber's UDR record; for example, the value of the last accepted MNO in the UDR record. The processing of the current message by the SoR application is now finished.