High call drops in a 2G cell due to TCH radio fail

Hello All.

We are observing high call drops in a 2G cell.

After analysis, it is observed that it is mostly due to TCH radio fail.

Also DL quality ratio is also less.

What could be reason for this?

Vendor is Nokia.


You have to check if cell is overshooting,0 is there alarm on site, if the kpi degrading suddenly or not, check HO, check installation.

Not sure about overshooting… No alarm as well.

It appears like the cell was added as a neighbour to few LTE cells and since that drop has increased. :thinking:

Are you doing CSFB to 2G?

Yes, doing CSFB to 2G.

Don’t you have colocated 3G site for your 4G RAT?

No, don’t have colocated 3G site.

Is it the highest priority for CSFB there?

So no 3G.

You have to check the TRX quality.

All the TRX affected?

No, priority is same for all 2G cells.


We changed the MA list also but drop actually increased.

High SDCCH drop also observed.

Due to radio fail also?

How is the HOSR?

It is 96%.

Check TAC LAC mapping in Core Side.

Exact reason didn’t see…

Only one cell is affected in that area.

Probably it will be correct only.

Will check anyway.

If not correct, the call will not establish.

Not the issue.

Check the HO cell to cell if any neighbors with same FREQ.

Also check BSIC.

MAIO step.

Check also the SACCH retransmission.

I also advise you to check the TRX quality through ZEEI to confirm if all TRX are impacted.

If yes you have to set the TRX with best quality as priority for CS.

And activate GTRX only on TRX with low quality.

I hope those steps can be helpful.

Is it possible to check TRX quality through ZEEI command?


Check both.

Not ZERO command?

ZEQO to set the TRP for service.

I think Yes.

Don’t really remember which command…
Can check ZERO, ZEAO, ZEEI

Check 196, 208 report.

It will show TRX Quality and Pathloss.