UE unable to reselect host PLMN

Consider a roaming agreement with the competitor network for the areas where we don’t have coverage.

When the UE loses the coverage of the home PMLN it should reselect to the host PLMN (Coverage is present) but UE is unable to do so, rather the UE is able to camp on the host PLMN after forced PLMN selection of the host network and able to make the call.

Any experience with this, are we missing something?

Did you try PLMN whitelisting?

Is this a feature? Core/RAN?

Hi @Mustafa_Rawat. Check with the competitor if your CN roaming parameters are defined in their MSC-S side.

Thanks @Tammam.Hajj. UE is able camp when it is forced to select.
Question is why it is not doing it automatically itself.
We are going to trace it with the host PLMN now.

Best choice to make the trace on the gateways between of both operators and good to trace a test UE/simcard to locate exactly the failure (it can be related to timers time out or mis- configuration).

In Ericsson:

hget PlmnInfo=1 plmnWhitList

Lists all PLMN IDs that are available for outgoing handover toward EUTRAN, UTRAN or GERAN cell and X2 setup.

Is it sim configurable we have different type of PLMN, i.e. HPLMN, EPLMN, OPLMN etc.

Make sure eplmn mapping is done is neighbor TAC.
3> define eplmn in HRL

This can be checked on 4G eNodeB and may be similar thing for a 3G Node.
What about a simple 2G UE not able to make it?

Is the other PLMN part of EPLMN list in Attach/TAU accept or part of SIM Preferred PLMN list, UPLMN or OPLMN?

It should be as UE is able to camp on forcefully.

Yes it’s part of usim.

Not necessarily, forcefully UE can try to camp even on FPLMN.
Check the SIM files related to OPLMN & UPLMN and also Attach/TAU Accept eplmn fields.
If these are not valid, then UE will search and attempt camping as per 23.122 : EHPLMN > UPLMN > PPLMN > Random PLMN as per signal levels.
In case UE is staying in Limited service, it might be trying to attempt on any random PLMN and getting Rejects.