How to route the call audio from the hearing aids to the Android smartphone speaker?

If the call was started directly on the hearing aids, it can be transferred back to the smartphone so that another person can talk to the caller.

This is how to reroute the call audio:

1) During the call, open the phone application screen (which is active during the call)

2) Look for the Bluetooth symbol and touch it to disable the call audio to the hearing aids.

3) Make sure to disable the symbol before handing over the phone to the other person.

It is important to not switch off Bluetooth completely, but only the Bluetooth symbol in the phone application.