Marrk
It's pretty easy to test. Whilst at home, or wherever you have access to a landline or somebody else's mobile, ring your mobile. You don't have to answer so there should be no cost involved.
Ring your mobile with Bluetooth (BT) turned on and then turned off. If I were a betting man, I'd wager it would make no difference at all. After all, many of us have BT on in order to play music in the car, for instance. I keep mine on all the time, in fact.
And just double check that you didn't inadvertently flip the side switch to silent. I've certainly done that. And also forgotten to switch it back to sound later on.
Ian