844-325-8795

This is the Citibank credit card fraud alert number - they called me to verify a charge.  If you call the number, you get a message that identifies them as Citicard early warning, followed by instructions on how to verify or dispute the charge they're calling about.  They do NOT ask for any personal info - they tell you which charge they're asking about and give you the last 4 digits of the card in question.  You simply press 1 or 2 if the charge is OK or not.