Western Washington will get a new telephone area code next year pending a vote of the state utilities commission. Idaho is rolling out a new area code as well.
The new area code in western Washington will be 564. In Idaho the new area code will be 986.
Population growth and the proliferation of mobile devices mean phone numbers for new customers are running out in Idaho's existing 208 dialing prefix and western Washington's 360.
The old way to provide relief was to split a territory and assign half the people a new area code. But now the go-to option is to "overlay" a new area code, said Washington Utilities and Transportation Commission spokeswoman Anna Gill.
"It's easier for customers because you won't have to have any customers change their telephone numbers," Gill said. "This way new customers are really the only ones that are going to be affected as far as having new numbers."
One consequence of an overlay, with its two area codes for the same geographic area, is mandatory ten-digit dialing for local calls, which will now include both area code and local number. That will be phased in before a new area code launches. In Idaho and the 360 area code territory of Western Washington, ten-digit dialing will at first be optional, then necessary later next year.
Last November, the Idaho Public Utilities Commission approved the statewide overlay of the existing 208 area code with the new 986 code. At the time of the vote, phone numbers with the 208 area code were forecast to run out in the second quarter of 2018, which has now been pushed back to early 2019. The plan remains to introduce the new 986 area code late next year.
The North American Numbering Plan Administration forecasts the 360 area code in Western Washington will be exhausted in the first quarter of 2018.
The Washington public utilities commission has scheduled a hearing on May 19 to consider options for implementing the new 564 area code with a commission order expected soon thereafter.
Initially, the 564 code will provide relief for the 360 area code territory. But WUTC staff has proposed to overlay all of western Washington with the 564 area code, so that it can also provide relief later for metropolitan Seattle-Tacoma-Everett, now served by the 206, 253 and 425 area codes.
Oregon and British Columbia have years of experience by now with area code overlays. In Portland, Salem and northwest Oregon, the 503 area code territory was overlaid with area code 971 in 1999.
In the rest of Oregon, the area code 458 provides overflow relief for the 541 area code. The first phone numbers with the 458 code were issued in 2011 in the Eugene area, but phone numbers with that area code remain rare.