Microsoft's genius
 

I'm running the WM6 ROM on my Apache. The contact database in WM6 keeps track of the last time you called someone, and that information gets synced with Exchange and/or PC.

So... if you have Exchange set to "As items arrive", and you call someone, the contact gets updated and Exchange tries to sync, and throws the error "Cannot connect: voice call in progress"

Gee, ya think??

I myself am syncing with Exchange 2007, and I am not experiencing the issue that you are describing. Can you describe in more detail what you did to prompt this error.

Are you in an EVDO or 1X area?

Next time you call someone who is in your contacts, switch directly to ActiveSync right after you hang up. Click "View Status" to see the error.

I'm not worried about it, I just thought it was funny to point out Microsoft's stupidity.

I'm in Ev-DO, but I doubt it makes a difference.