Starting next month, Mercer County residents will have to dial the area code in order to make a phone call.

A new dialing produce is set to go into effect on Aug. 18 that will require callers in the 609 region to dial the 609 area code before the telephone number.

The changes are a result of a new area code being approved by the New Jersey Board of Public Utilities. The area code — 640 — will be given out to new numbers in the same geographic region as the 609 area code beginning in September.

Callers will have to the dial the area code with the seven-digital telephone number in order to successfully place a call.

In addition, calls made from the 609 area code to the 856 area code (southwestern New Jersey) that are currently dialed with seven digits will need to be dialed using 1 + area code + telephone number.

For more information about the changes, visit Verizon’s website.