CFSB to 2G KPI Ok, but no calls (CFSB not happening)

Hi Experts,
CFSB to 2G, KPI is showing fine, but calls are not happening.
What can be the issue?
CFSB execution rate is 99 percent.
Vendor is Huawei.

Is the call setup failure or is happening in 3G?

Alt LTE end, call setup from LTE is not happening.

Calls to CSFB Subscribers Fail Due to Incorrect Adjacent Cell Configuration

A circuit switched fallback (CSFB)-capable mobile switching center (MSC) server sends a paging request to a 4G subscriber over the SGs interface after a call is placed to the subscriber. However, the CSFB-capable MSC server does not receive a paging response from the subscriber and then releases the call. This is because the radio network controller (RNC)/base station controller (BSC) is not configured with the 4G neighboring cell data.

Any Core issue possible? (KPI showing 100%)

Do you have UE logs for it?
I mean do you see extended service request, RRC connection release with redirect information?

No extended.
But KPI is 100% (L.csfb.e2g is 100 percent).
With prepatt.

Already checked with neighbor site, calls are happening.
With same TAC and LAC.

That means there is extended request and also release with redirect.

Yes, as per KPI no issues.

Is this happening per MO or MT calls?

Once in bloom it takes neighbor 2 sites.
2G is working fine.
As 2G defintiton and 2G nbrs are defined.
But RRC requested showing high priority access in logs.

For MO & MT, UE should initiate call in 2G after redirected from LTE.
You should check UE logs why UE doesn’t do this.
I mean NAS layer, inside the UE.

After setup, no complete.

This is not the right behaviour…

It’s not normal.
It will not take CSFB.
Or any other technology.

No complete after setup?
It means your uplink is poor, or check alarms on 2G cell.

Yes, I think RSSI maybe in 2G.

Could be, but this could be checked in counters in 2G.

But LTE end is fine - at LTE end CSFB happens.

Check the 2G call setup success rate.