They left no message. Caller ID says CERT GOOGLE PTR. When you call the number back, a recording by an unidentified company says, if you would like to have your number input into our Do Not Call database press 1 now. The recording repeats a couple of times, then hangs up on you. There is no way to talk to anyone. Obviously any company that answers their phone this way is a scammer!
BTW, Panasonic makes some good call blocking cordless phone sets, such as the KX-TG454 SK or KX-TG465 SK which both block up to 250 phone numbers. The Ooma phone system blocks 254 phone numbers and the T-Lock Call Blocker, which connects to your phone line, blocks 1500 phone numbers. You should check them out on eBay or Amazon if you want to block telemarketing calls. Hope this helps.