Cell Phone Time Zone Locator

Cell Phones are great for travelling. They permit us to recieve calls where ever we go without informing everyone of our local phone number. Unfortunately, travel permits us to recieve calls at 5:00 am on the west coast from some insipid character who did not know we left the east coast. I propose a new add on service for travellers that will, if a call originates in a different time zone and the local time is within the customers prescribed hours, inform the caller of the local time where the recipient is before the call is completed. "The person you are trying to call is currently Time Screening their calls. It is 5:45 am at the reciepients location, please press 1 now to complete this call." This way, when they do wake you up, you know they meant to so you don't have to feel bad about being rude to them.