American Express is about to change its terms of service agreement allowing them to call or SMS you on ANY number you call them from. What this means is if you borrow a friend's phone, use a pay phone or a hotel phone to call the company, they can call that number back in reference to your account for any reason. This is not to imply AMEX would divulge your confidential information but the problem here is the lack of respect for customers American Express is displaying with this move.
Moreover the utter stupidity of this change from a CRM perspective makes you wonder as an investor or customer whether you want to be associated with the company at all. BTW I am a very satisfied customer of AMEX myself and these rules won't make me cancel (yet) but they will make me wary of where I call them from.