Help Using speaker phone causes dropouts

[joebone]

I generally use the speaker phone while driving. When I started using the Droid X several people told me I was dropping out, very choppy, hard to understand. My end was fine with no dropouts.
When I turned off the speaker phone in the middle of a call, the dropouts stopped.
I have the latest update, good strong signal. The other party is on land line or Verizon wireless.
Any ideas?
Thanks