UE locked in 2G cannot make calls in 4G/3G/2G layers cell

Dear Expert,

An interesting thing observed during DT:

A cell having all Layers 4G/3G/2G.
CSFB happen normally on the cell.
If you lock the mobile on 2G, call not connected to this cell.

We are on the main Lobe of the cell.
2G Coverage also not showing on this specific cell, 3G/4G it showing normally.
Physical audit has been done, no abnormally showing.
In Stats it showing nearly zero Traffic.
Neighbor cells having high traffic due to this issue.
Paramters audit has been done.

What could be the posible reason?


Check if traffic is directed to 3G.

It is on default setting.
Do you mean Mean 2d/2f?

Check other cells where same settings applied, do you face same issue?
If not, so it might be resources hanging at 2G site, a BTS restart may resolve it. (But make sure that this problem only at this cell not at network level).

Already done. Soft and hard reset.

And this is happening only in this cell, but same parametric value on the other cells.

Check 2G TCH Assigment rate, may be due to congestion.
Also chech CSFB happened with same 2G cell or other 2G cell.

No traffic no congestion.
CSFB enabled on 3G.

SD slots issue may be.

Check if trx is ok, or have alarms.
Check territory Edge and Gprs.
Check sdcch distribution.
The 2G UE see the site or no? In idle mode for reselection?

No alarm at site.

If you lock your phone on 2G, can you handover to this cell?

Check cell barred.
Check LAC definition in MSC.

Cell barred does incoming ho?
As in LTE it’s with sib1 msg to chk.

Mobile is not supported to lock the specifi BCCH.

Don’t lock into a specific BCCH.
Lock on 2G RAT.
And get in the main lobe of the cell.

Yes, it do.

No barred.

Yes, i did… but 2nd sector will serve.

Maybe it is not defined from CORE side.

On stats, just 5 to 6 MOC on daily basis.

Check definition at CORE end.
LAC and CI.
MOC calls will be zero and low traffic is only handover.