Lowcountry and Pee Dee residents with the 843 area code will have to dial at least 10 digits to make a phone call starting on Sept. 19, 2015.

That's the date that's now been set for mandatory 10-digit dialing, as part of the phase-in of a second area code serving the same region.

Coastal South Carolina and some inland areas are getting a second area code, 854, because the 843 numbers will soon run out. It will be South Carolina's first "overlay" area code, which means the same region will have two area codes instead of one.

Overlay area codes already are common in large cities, which may have multiple area codes.

No one will have to change their phone number, but with two area codes serving the same locations, all calls will require dialing an area code.

A schedule for the roll-out of the new 854 area code was sent to state regulators Tuesday by the North American Numbering Plan Administration, which oversees area code issues.

Here's the schedule:

By Sept. 13, 2014, begin customer education and begin preparing networks for the overlay area code.

March 14, 2015, begin permissive 10-digit dialing. That means people in the 843 area code could dial an area code while making a local call, or not. It's a break-in period meant to get people used to dialing 10 digits.

Sept. 19, 2015, mandatory 10-digit dialing begins. All calls made by people who have the 843 area code will require dialing an area code.

Oct. 15, 2015, earliest date the new 854 area code will be activated.

For cellphone users, the change may be no big deal, but folks with land lines will have to get used to dialing an area code to reach a local number, even if it's their next-door neighbor.

Dialing an area code to make a local call will not increase the cost of making the call.

Reach David Slade at 937-5552