Whidbey residents may see phone-related changes in the new year.

Phone companies will begin issuing a new “overlay” area code in Western Washington, possibly beginning at the end of the year. The 564 area code will be added in areas currently covered by area codes 360, 206, 425 and 253, according to the Washington Utilities and Transportation Commission.

Current phone numbers won’t be changed. The new area code will be used when phone companies issue new phone numbers.

The reason for the change is that the federal Communications Commission Numbering Plan Administrator predicts that unique phone numbers in the 360 area code will be exhausted in 2018. Phone numbers in the area code are becoming exhausted faster than earlier estimated.

“In recent years, a combination of new technologies and increased consumer demand for regular telephones in homes and offices, cellular and PCS phones, pagers, lines used for fax machines, modems, internet access and other uses have strained existing telephone number resources,” the North American Numbering Plan Administration reported.

A side effect of the new overlay area code is mandatory 10-digit dialing by the fall. That means that people in the region will have to dial the area code even for local calls.

State and federal regulators have implemented measures to increase the efficient use of the existing supply of numbers, such as number pooling to allow up to 10 companies to share a single telephone prefix.

Federal regulations require all service providers to allow customers to keep their existing numbers when there is a change in service provider, location or service.