Using Google Voice with a ported phone number allows a cell phone to be hardwired via Ethernet for calls and texts, even when the phone itself is on airplane mode.

“because Google Voice is an internet-based app that allows you to do text and calling otherwise you can't do Wi-Fi over calling through the ethernet you got to use Google Voice or like WhatsApp or signal one of those internet based apps will allow you to communicate”

“if you use Google Voice or these other apps you can make a call through the internet based services and you don't actually need to have Wi-Fi on at all”