I answered the call once and it was a gentlemen from an Safelite Auto Glass asking whether I have any cracks or chips. I told him that I didn't need a new windshield and hung up. I had ignored the call several times before answering and he's called back several times Since I've answered. I get the same when trying to call the number back; "You have reached a non-working number".
Same here, shows Walmart on the Caller ID, but says the number is not valid if called back. Doesn't sound like the message the local communications companies use, so I would guess the message is actually the business picking up and pretending the number isn't working.