Standby means you are required by your employer to be prepared to report immediately for work if the need arises, although the need may not arise. According to RCW 41.37.010 (6)(b)(vi):

(1) The pay you receive for being on standby qualifies as reportable compensation; however

(2) The time you spend on standby is not counted toward service credit and is not reported to the department by your employer.