They call multiple times per day, usually in the evening and on Sunday. Caller ID just says Bellevue, WA. I don't pick up and they don't leave message.
If you have WaveBroadbands service, looks like you can block or "reject" up to 12 numbers. I just did it after being woken up likew 3 times in 55 minutes. (shift worker) I answered it once and it said something about BBC service or survey maybe (unknown if it's the BBC network or not), I hung up and they called back a few minutes later... Anyway.. I'll find out soon enough if my phone provider's reject service helps or not.