Who called from 3603226221

Ive gotten calls from this number about 2x a month for about 8 months now.
There is never a message left.
When i've tried to call back it says the line does not accept incoming calls.
I've done the lookup and the google locater and it comes to a
SPAM CALL CENTER IN WASHINGTON STATE (KENT,WA).

Same thing for me.  Called me at 10:26 AM today on my cell phone.  No message.  Tried calling the number back from my work phone and it won't go through.

Got my first call from this number today, on my cell.  I don't know the number and no one left a message.  I called back from my work phone and a message stated "thank you for calling us about our marketing promotion".  Updating my cell fone as...don't answer.

Got a call from that number as well, answered and nobody there.
I now have it marked as 'SPAMMER' on my phone.

No message,just a hangup when I tried to answer. They are now in my address book as spammer. I just wont answer it anymore.