the phone shows "cell network indicator" ON but there is no telephony possible

[Chris]

I have had a stange bug on my Meizu Mx4 at least 5 times till ota 5 ... but I wasn't able to reproduce it ...till yesterday

It generally occured after a screen freeze ...

my tel connection in task bar was ok : cell network icon triangle "filled".. ON but in fact the telephony service was not functional
- when making a phone call there was "no connection available" when in the "phone call screen" ..
- The people that called me during the problem heard the ring several times ..but I didn't receive any call or msg on the phone.. so i was probably connected to the cell network cause my account was receiving calls and they were not redirected to the message box directly.. but on my side the phone didn't ring nor receive msg

-> I have tried to use plane mode on/off / changing the sim card /reboot ... nothing worked .. then after some times it returned to normal ...

The main problem here is that you consider that the phone is working cause you see the triangle icon full in the indicator bar ...
But you don't receive the phone calls ... like if you were ignoring phone calls

Yesterday I found a way to reproduce the bug ... and the workaround that makes the telephony-service work again after the bug

how to reproduce the problem :
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1. put wifi off and phone data off (2g/3g/4g)
     telephony triangle icon is filled

2. restart the phone

3. after restart the phone indicator bar shows full GSM cover with the triangle icon filled.
4. if you go in the phone dialer ... you have no network .. you can't make phone call .. and you can't receive phone calls nor sms

Workaround: (to get your gsm back to normal)
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to make the telephony work again :
it's odd put you must only put wifi "on" from the indicator bar
then telephony is functional again... and you get the operator name in phone app

Kind regards