[RKDinOKC]

They were also considering putting sensors on peoples offices to determine how many people were in the office and whether the door was open or closed.

The number of people in the office and whether the door was open would determine how calls were routed. Example:

No one in office, door open or closed - voice mail
One or more in office door open - ring thru
One or more in office door closed - voice mail

And this could be combined with the RFID to tell what outgoing message would be used when sending to voice mail.