I already know this information.
The issue is that there is no direct relationship between a Location Update failure message as received by the MS, and the error code as sent by the HLR.
For instance, the HLR has no way to know the Location Area code of the MS. Yet, the MS can receive “Roaming not allowed in this LA” or “PLMN not allowed”. So the decision to send either code cannot come from the HLR, it comes from somewhere else, and I want to know where.
(unless I’m mistaken)