A couple of excerpts:
“While we are driving, we are bombarded with visual information. We might also be talking to passengers or talking on the phone,” Marois said. “Our new research offers neurological evidence that the brain cannot effectively do two things at once. People think if they are using a headset with their cell phone while driving they are safe, but they’re not because they are still doing two cognitively demanding tasks at once.”
“I’m Australian, and it’s illegal there, so I’m trained not to,” Dux said. “Even so, I would never do it. Dual-task costs can be up to a second, and that’s a long time when you’re traveling at 60 miles per hour.”
If you must talk on the phone, pull over. It’s that simple.