Ohio's largest area code is getting a new number.

Beginning March, 2015- all new phone numbers in the existing 740 area code will get a 220 area code.

Existing numbers will stay the same, but Public Utilities Commission of Ohio spokesman, Jason Gilham, says there will be a key change for all callers. Those calls will require using the 10-digit phone number to even make local calls.

The 740 area code was projected to run out of numbers by the second half of 2015. Gilham says ten digit dialing will be phased in starting next September.

The PUCO decided to go with an overlay instead of splitting the 740 area code up.