RCW 19.190.060
Intent-2003 c 137: "The legislature recognizes that the number of unsolicited commercial text messages sent to cellular telephones and pagers is increasing. This practice is raising serious concerns on the part of cellular telephone and pager subscribers. These unsolicited messages often result in costs to the cellular telephone and pager subscribers in that they pay for use when a message is received through their devices. The limited memory of these devices can be exhausted by unwanted text messages resulting in the inability to receive necessary and expected messages.
The legislature intents [intends] to limit the practice of sending unsolicited commercial text messages to cellular telephone or pager numbers in Washington." [ 2003 c 137 s 1.]