I just called the Attorney General's office of consumer protection, 800-441-2555, and the person said that  888-567-8688 is a real opt out phone number, it is NOT a scam.  It will opt you out of all 4 credit bureau's submitting your name & address for pre-approved offers and loans.

Is it a legit number?

I just got an application for a City Bank Credit Card. The opt-out number was on the card. I called it and gave info up until they asked for my social security number. I will NOT give that number out. Whether it is a scam or not, I don't know. I followed the info on one of the responders here and did see that the opt-out number is listed on a government form. Does this mean it is legit, or does it mean the government has been compromised? I honestly don't know but I will not take the chance of losing my identity. And neither should you. It virtually will destroy your entire life, maybe beyond repair. Be careful out there. The US is among the most corrupt country on the planet now.

THIS NO. WAS AT THE BOTTOM OF A PAGE TO OPT OUT ON A FORM I GOT THRU THE MAIL FROM 21ST CENTURY INSURANCE.SPONSORED BY PUBLISHERS CLEARING HOUSE.  I CALLED THE NO. TO OPT OUT AND IT ASK YOU TO VERIFY YOUR PHONE NO., YOUR ADDRESS, YOUR NAME BY SAYING YES OR NO, THEN THE RECORDING ASKS YOU FOR YOUR SOCIAL SECURITY NO.  ALL OF YOU PEOPLE OUT THERE!  IF THIS IS NOT AN ATTEMPT TO STEAL YOUR ID, THEN FOR HEAVENS SAKE TELL ME WHAT IS?  NIKKI IS CORRECT AND I AM A DIFFERENT SAM FROM THE ONE THAT ANSWERED HER EARLIER, AND WAS A VICTIM OF STOLEN ID SEVERAL YEARS BACK.    KEEP UP THE GOOD WORK NIKKI

The number is legitimate. Go to US Gov website: http://www.ftc.gov/bcp/edu/pubs/consumer/credit/cre17.shtm
Also you can type number into www.snopes.com and you will read many false
Claims folks have made about this number but as you read they explain how it works.

Well goddammit Nikki.  Way to talk out your a** on something you literally know nothing about.

It is a legitimate number and can be found on various government websites. This one is for the state government of Rhode Island.

http://www.risp.ri.gov/idtheft/

This is not a scam.  This is a legitimate way of opting out of those pre-approved credit offers you receive in the mail.

This number was on an "advertisement" i received in the mail.  I have gotten several different types, free cell phones, pre-approved credit, etc.  At the bottom of the page, it says to call 1-800-5-OPT-OUT and that your name will be removed from their database, to prevent any future offers.  When you call the number, it says it is operated by the Consumer Report Agency.  The first thing they say is that a live representative is not available, no matter what time or day you call.  Basically, they ask you to input your phone number, address, and then confirm your Social Security number.  I am assuming they follow up by stealing your identity.  I want to give people a heads up about this, this is a huge scam.