Yeah thanks for that, I have to say the CS agent did not mention it but I had already read that elsewhere(probably on here) and also knew it from having had one on my previous mobile network.
We left the killing fields of East London to live in the farming fields of Lincolnshire a couple of years ago so been using an O2 boost box since we did and was most satisfied with it for the entire duration we've had it. The frustrating thing is part of the reason we moved over to BT Mobile is because it's meant to be much superior round this area and although BT/EE are better than O2 it's still not all that if I'm brutally honest.
Saying about WiFi calling, I just can't get on with touchscreen which means I am one of those dinosaurs still rocking a BlackBerry and though they run on Android these days and I have got the most recent release, the Key2 LE, it's not compatible so haven't got any experience on that front but seem to hear loads of people saying it's not very good. She recently bought a Galaxy A70 which I think does do Wi-Fi calling but she's not tried to set it up either, we'll just wait for the Signal Assist to arrive and kick in.
DPD delivered it at around half 10 yesterday morning so hooked it up straight away and just noticed I got full bars on my signal display so it took 24 hours which ain't too shabby all things considered.