tzippi, I wasn’t responding to the problem of driving, I was being dan lechaf zechus about people in the Bais Medrah with Bluetooth. I have friends in Yeshiva who learn over the phone using bluetooth with people from across the country (parents, Partners in Torah, etc).
Side point: In the car is a good time to talk on the phone since you have “time to waste” anyway unless you would be listening to a shiur or doing other productive things otherwise. If there are calls that you need to make then why not do it in the car when you have the time instead of during work or at home when there are better things to be doing. Of course it should be done in a safe way; use handsfree, only dial while stopped, etc. And you certainly shouldn’t be texting while driving as this takes more concentration because you actually have to look at the phone to see what you are doing. Talking while driving could also prevent the driver from falling asleep late at night.