Bit of a twist to those positive and negative responses above. "Monica from Amex" calling to verify personal info regarding my Amex Open card.  Asked for last-four of SSN, address, corporate structure, and Tax ID #.  I told her she already had all of that info from my initial application, and ended the call.  I called the Amex number on the back of the card and spoke to a CSR.  While she said the phone number was one of the corporate numbers from their Salt Lake City office, Amex NEVER calls to validate info, and that this info would be passed on to their Fraud Office.  Bottom line: NEVER give personal info over the phone to anyone you didn't call.

I applied for a Amex card through Costco website. I received an email asking me to call a 1888 number to confirm addess, then received a call from this number asking for my last 4 digits of SSN, home address and name of my bank. This call was suspicious to me, so called amex consumer service. They directed me to a 1800 # for new card. Apparently, the agent is in India and confirmed that they have a call center in Utah. The Indian lady confirmed the information I just gave to the Utah lady through the phone call. It seems that this phone number is not a fraud, but I am very concerned with how Amex do business.

It is a real # from Amex. I checked with the customer service.

It's most definitely American Express Customer Service.  They called me to verify a gift card I had purchased.

AMEX. They knew the card name I applied for. Called me because of Fraud Alert on my credit file.