If you would like your InnoCaption call audio to automatically go to your Bluetooth device (such as a hearing aid, cochlear implant, or headphones), you can manually change your default sound output settings for all calls. Please note that this will also change the default option for calls made or received through your regular phone dialer as well.
To change your default sound output setting on iPhone
From your home screen, open the Settings app
Tap Accessibility
Tap Touch
Scroll down and tap Call Audio Routing
Select Bluetooth Headset