Ever since cellular phones came along, I've always used a BT headset. Even on my first flip phone, which did NOT have Bluetooth
I used one. Plantronics made the M1500 which was a two piece headset. The headset was wireless, and the other part plugged into
the earphone jack on the phone.
I've always used either handsfree or BT headsets when using the phone. Not out of caution, but back then, there wasn't speakerphone
mode or connecting it to your car.
So if you needed to answer a call, you had to hold the phone up to your ear, which wasn't really a good thing to do while driving. Especially
when your work vehicle was a manual transmission.
It's just habit now to pop on the BT headset if it isn't already on my head.