Adjusting cell phones for driving time

We all know that driving and talking on a cell phone isn't the wisest thing to do. The problem is that we've become conditioned to expect uninterrupted connectivity with the rest of the world. If the cell phone rings while you're driving, you know that you don't have to answer it, but you want to because it's what you do. We don't learn to ignore the phone, we learn to answer it. We also anticipate that if we don't answer a call, one of the following might happen:

• The caller thinks we're screening them.
• The caller thinks something might be wrong.
• The caller thinks our phone is off.
• The caller will give up and try our home number.
• Our brains might explode.

These are possibilities, but what's most likely to happen is that the caller will either leave a voicemail or try calling again later. But I think there is an opportunity here that either the cell phone service provider or cell phone manufacturer could take advantage of.

I'd like to be able to instantly switch my phone into 'I'm busy driving' mode. When the phone (or service) is in this mode, any incoming calls are immediately routed to voicemail and an announcement indicates that you're busy driving and can take the call in x minutes. Maybe assign the asterisk key to this function:

**5 - The announcement says please try again in 5 minutes
**20 - Please try again in 20 minutes
**180 - Please try again in 3 hours