Think about the way you dial a phone number when you are in Eastern Washington.

When you dial your phone to call someone in the 509 area code you don't have to dial in the area code. But that's changing. You'll soon be required to dial in the area code before the number. In fact beginning October 24 if you make a call within the 509 area code and don't dial in the area code the call may not go through. In July 2022 service providers will completely remove seven-digit dialing from their networks so they say get used to dialing the 10-digit code Today.
Why the change? A press release from the Washington Utilities and Transportation Commission says the "change to 10-digit dialing in 509 is a first step toward ensuring that everyone in the country will be able to reach the National Suicide Prevention Lifeline using a three-digit code of 988 that launches in 2022.

Requiring the area code will also ensure that customers who already have 988 as the prefix in their phone number don’t have trouble making or receiving calls once the new three-digit dialing shortcut launches. No phone numbers will change because of this order."

The 509 area code is the last to make the change. In 2017 all area codes on the west side of the state switched to 10-digit dialing.
Beginning July 16, 2022, dialing “988” will route calls to the National Suicide Prevention Lifeline. Until then, callers can reach the hotline at 1-800-273-8255 (TALK).

36 states are transitioning to 10-digit dialing in a total of 82 area codes to prepare for the 988 hotline.