Multivendor (ZTE Nokia) Reselection Issue

Dear Experts,
I have an interesting case.

I have two sites:
One site is ZTE_3G and another NOKIA_3G-4G.

I do a Handover in ZTE site: HO ZTE_3G <-> NOKIA_3G site. And when it the call finish, it don’t do reselection 3G to 4G NOKIA.

But when I Originate a call in NOKIA_3G, after call finish it do reelection without problem to NOKIA_4G.

The question is: Why it does’t to reselection 3G to 4G NOKIA in the first case?

I think maybe after the call finished, the Re-Selection priority back the call to the 3G ZTE site before 4G.
Did you check 3G-3G reselection parameters?
You can try with remove relation in the way from NOKIA - ZTE.
And try again.

No, the UE is in 3G NOKIA.

It can be because of higher reselection priority on ZTE freq.
After call release, the highest priority RAT is selected as per strategy.
LTE being the highest should go.
So you need to check the CRP.

So both call end at 3G NOKIA.

1st case call start at 3G ZTE.
2nd case start at 3G NOKIA.

I think you should start to check how 3G-4G performed at 2nd case.
through which triggering condition.
Then you can analyse why it doesn’t work at 1st case.

When the call ring (begin) in ZTE the UE are in idle or doing a data session?
For your explanation this happens sometimes when the UE don’t release all services (E-RAB)…

It is in idle.
It is possible that mobile don’t release all services.

When the UE move from ZTE_3G to NOKIA_3G maybe same services don’t move to NOKIA side.