A target phone number previously associated with a first user is presently associated with a second user such that the target phone number is not presently associated with the first user. A caller uses a calling phone number to initiate a phone call to the target phone number. In response, it is determined whether the calling phone number is on a list of phone numbers associated with the first user. If the calling phone number is on the list of phone numbers associated with the first user, then the caller is notified that the target phone number is no longer associated with the first user. It is determined whether the caller wants to continue with the phone call, and if not, the phone call is terminated before it reaches the second user.