Single ear devices are usually legal where earbuds in both ears is not. Maintaining situational awareness seems to be the rule. If course, I'm essentially deaf in on ear, so being legal isn't any safer.
I tend to use the car speakers or simply refuse all incoming calls while driving.
> simply refuse all incoming calls while driving
Definitely the best course of action. Even just talking on the phone is very distracting. No way someone can have a full conversation going and still be giving the same attention to driving.
I’m pretty sure this is rarely enforced in most states in the US. My father frequently drives across the US and always takes his calls with earbuds because the speakers aren’t very good.
I do it with one earbud in because I find the quality of speaker audio terrible, forcing me to concentrate harder on it to discern what’s being said.