dropped calls

[Mau]

Hi, before i joioned O2 i did the network coverage checker and everything upto 4g says good indoors and out yet why do i still keep dropping calls and often sound like Norman Collier during calls (voice breaking up for you young uns)?

I've bought a new phone thinking it was a possibility and yet the new phone is just the same

neither phone is on the wifi calling list although they do make wifi calls through a BT sim ive since tried, can anyone think of anything i can try to be able to make calls withoput dropping out or is there any way to be able to use wifi calling if your phones not on the list, its an android phone running android 10

[Cleoriff]

@Mau 

The first thing I would do is get a new sim.

You can get one instore or by contacting O2. All numbers in this guide Guide: Coronavirus Community Help and Support 

[MI5]

@Mau 

The network check online is just a computer simulation of theoretical coverage.

We always recommend trying with an actual SIM to check real life coverage as you are now finding out.