Delay between speaking and other person hearing

[YellowFunky]

I've been with Sky for quite some time and I've had problems with there being a delay between me speaking on the phone and the other person hearing me. Most commonly this happens after about 10 minutes into the call and more recently it's starting to happen after just 30 seconds. 
move changed devjces following an upgrade, changed SIM cards and now am using an Esim but the problem is still happening. 
I read somewhere that WiFi calling could cause this delay but I've no idea how to see if I'm using cellular or WiFi calls. 
I've spoken to apple about this and they've suggested this isn't a problem with the device. 
anyone have any ideas of what to try or if this post might be picked up by a sky advisor?

thanks 

[63johnw]

Hi @YellowFunky  to check if you have WiFi calling on or off go to settings, mobile service, scroll down to WiFi calling and toggle on or off. 

[caesarome]

@YellowFunky 

On your iphone if you've downloaded the latest software go to Settings > Phone > Wi-Fi Calling and slide the button to green to turn it on or slide it left to turn it back off.