Full signal bar but can't make call or receive call

Question

I have issue on my Xperia Z phone, when I went to my work area that do not have the netwok coverage for some time, after get out from the area, the signal bar is resume back to full at notification bar with h+ (sometime LTE) and signal strength is about -73dbm but the phone is not able to make call or surf net, can't even reachable when someone try to call me which my friend keep complaint to me eventhough during that time my phone is actually showing full signal on the notification bar, checked this with my colleague which using the same model phone and he do have the same problem, the problem is sometime recovered by switching to Airplane mode and switch back to normal mode else need to power off the phone and power on again. Already sent the phone to sony and they have reinstalling firmware and end up still having the same problem. Anyone know how to fix this issue or will this issue fix with the 4.2.2 update? The area that I stay still do not have 4.2.2 release yet and my phone is currently running on 4.1.2 with 10.11.A.1.253 build number. Tried verified same sim card on my wife's htc one phone, not found this problem. If sony still not able to fix this issue for me, this will be my last Sony phone and say byebye to sony forever and welcome htc!!

Answer 1

No bars for me if the phone have been searching for a network in a place with poor coverage. It might not find any network at all if I do a manual search, only a restart helps. Luckily i'm not in such places very often. Xperia ZR, most firmwares up to .230. I woun't go into the woods and try to disable network types to try to troubleshoot, nor replace the simcard. With Telia i'm often connected to GSM. I think these phones are better with GSM turned off, would be nice to be able to turn that off (not the hacky way in the service menu). Maybe something bad happens when the amplifier is forced to transmit at maximum power, GSM signals are nasty!