I have walked behind countless people in shopping malls or on the sidewalk while they are talking on the phone. These talkers are weaving like drunken sailors and bumping into other pedestrians. People are swerving out of their way to avoid colliding into them. The talkers often stop suddenly to get their bearings, gazing about with a look of wonder that clearly says 'How did I get here?'
You can't even walk and talk on the phone. What the hell makes you think you can DRIVE and talk on the phone?!
I know there are times when you need to make or take a call. I've done it. But having an entire conversation while driving is not appropriate.
Make the call that tells your spouse/boss/children that you're running late, but make it quick and hang up. Don't call your friends to pontificate on the meaning of life or chatter on about the great sale you were at last week. Don't call clients to close that big deal.
Besides, if you want to properly gossip with your girlfriends, then you really should have a good glass of wine or a martini in your hand! And I'm pretty sure there's a law or two against doing that while driving.