Yes, confirmed today 12/1/2009 that 800-592-1160, 866-231-9049 and 623-492-6031 are all American Express numbers -- genuine. Some are unlisted numbers but they are all part of AmEx. It's not totally clear why they have hidden numbers or why they are calling people asking for SS# and card numbers. AmEx clearly states on their web site that they never call and ask for your full numbers -- but that is exactly what they are doing. I just spent several hours with them on the phone today talking to their fraud department, because at first I suspected this was a scammer. But these are all originating from AmEx. Even more bizarre is that the fraud dept kept asking for my SS# also (even though I don't even have an account with them). Obviously I didnt' give it (never give this out). They call me from this number all day and night.
The bad news is that they seem to be robocalling everyone in the U.S. -- maybe trying to sign them up for AmEx (motivation not clear). Very annoying because they keep calling even though I'm on the do not call list and have asked repeatedly not to be called. They call on average every few hours for the past few weeks.
The good news is that you can easily sue them for $500 per call. I'm doing this right now, and will post my results when done -- but others have done this successfully. It's very easy and cheap to do. In NY, just stop by the courthouse, fill out a very simple 1 page form, and pay $20. Since they called me 7 times in the past 48 hours, I'm suing for $3500 + the $20 court fee.
Robo-calls to a home phone number is illegal (except for charities and political campaigns). So if AmEx called you and you didn't ask them to -- you're entitled to $500 per call. It's an easy way to make money and also tell Amex not to bother you again. When you fill out your small claims paperwork -- just mention they are violating the Federal Telephone Consumer Protection Act (TCPA) -- which clearly states that automated calls are illegal. If you are on the Do Not Call registry, or have asked them to stop calling you in the past, you may even be entitled to more money.
This only takes a few minutes, and is easy to do -- so please give it a try. If Amex has annoyed you with their repeated robo-calls, this is a great way to get some justice -- and some extra money. Best of luck!