Wash. Rev. Code § 24.06.150
Meetings of the board of directors, regular or special, may be held either within or without this state, and upon such notice as the bylaws may prescribe. Attendance of a director at any meeting shall constitute a waiver of notice of such meeting except where a director attends a meeting for the express purpose of objecting to the transaction of any business because the meeting is not lawfully called or convened. Neither the business to be transacted at, nor the purpose of, any regular or special meeting of the board of directors need be specified in the notice or waiver of notice of such meeting.
Unless the articles of incorporation or bylaws provide otherwise, any or all directors may participate in a regular or special meeting by, or conduct the meeting through the use of, any means of communication by which all directors participating can hear each other during the meeting. A director participating in a meeting by this means is deemed to be present in person at the meeting.
RCW 24.06.150