I don't know whether this is applicable but on my iPhone, I had to to into Accessibility, down a bit there is a setting called "Call Audio Routing". I have that set to Bluetooth Headset. This will route the sound through the Bluetooth device when it is available. I have a handsfree device that connects my iPhone and iPad and all sound goes through the speakers for calls and Copilot directions.
Goody Two Shoes and the Filthy Beast
2008 Silverado 2500HD
2012 Wildcat 282RKX
You cannot make things idiot proof, you can only make them idiot resistant.