UPDATE: The 866 number is valid for Citi Bank. THIS NUMBER IS NOT! I just got this verified by Customer Service at Citi Bank from the number on the back of my Brand NEW card. BEWARE:, If calling your bank, if they ask for your entire card number not just the last 4 numbers or not just the last 4 of your social when your calling from the phone that is tied to your account. ALWAYS just hang up.