I've received about 10 calls from this number in the last 2 weeks. The caller ID says "comm serv for" and when I call them, they just have an in-house busy signal (i.e. they recorded the telephone company's busy signal and play it back as a pre-recorded message).
Received one hang up call on my answer machine, Jan 6, 2008. No caller ID. *69 revealed 206 268 6636. I googled it and found this site, and have not called it back.
It is Community Services for the Blind, a not for profit donation center. I donate as often as I can so I know their number well. They come pick items up you want to donate. The call is to say they will be in area and to schedule if you have anything to donate. They employ ppl with some disabilities to do calling so I try to be polite and kind to them, where I may not be with others. They are just tryin to make a living.