Telephone customers are about to see a lot more about the area code overlay that will make 10-digit dialing mandatory later this year in southern Indiana.

Telecommunication providers are scheduled to give a Feb. 1 notification to their customers about the overlay, which will mix new telephone numbers with a 930 area code into the existing 812 region.

But some mailings that spell out important dates and new dialing instructions already have gone out in the mail.