Bug #6099
closedImmediate Assignment on PCH without IMSI (check back behaviour)
100%
Description
It may happen that the PCU tries to perform an ImmediateAssignment even though it does not know the IMSI yet. At the moment osmo-bts rejects those ImmediateAssignment (PCUIF) requests since without an IMSI we can not properly calculate the paging group. However, since we discovered ImmediateAssignments without an IMSI in the wild we need to check back if we changed the behavior when moving from PCUIF v.10 to PCUIF v.11. And if necessary we should make sure that the behavior we had before the change is restored.
The specs seem not to be entirely clear about this, here are some references:
3gpp TS 44.018 3.5.3.1.2
3gpp TS 44.060 5.5.1.5
Related issues
Updated by dexter 5 months ago
- Status changed from New to In Progress
- % Done changed from 0 to 50
I have checked back the behavior that we had before. It was indeed different. Even a shorter IMSI would have been tolerated back then. The calculation result would have been wrong but since osmo-pcu would always ensure leading '0' when sending the first three IMSI digits there was no problem. The following patch restores the behavior we had back then:
There is now a patch for osmo-bts in gerrit: https://gerrit.osmocom.org/c/osmo-bts/+/33766 paging: also accept IMSI strings shorter than 3
