(Columbus, OH)--The new area code for southwest Ohio, including Preble County, has been determined. Earlier this year, it was announced that the 937 area code is running out of numbers. Beginning in about a year and a half, new phone numbers in Preble County will begin with the area code 326. That number was announced Wednesday. The new area code will apply to new numbers only. People who already have a number with the 937 area code will not have to change.