So far received 2 calls from this number within 8 hours, did not pick up. I blocked my ID and called the number back. It is not a valid US phone number.
I tried 1-800-654-9230
(compare to 1-800-432-3117
, the number Chase gives for Customer Service) With some experimentation I discovered it requires a 13 digit account number. On the first attempt, I was put on hold "for an available representative" before being cut off. Typical hold music, but slightly glitchy voice playback. Could have been recorded from elsewhere. "If you feel your call has been cut off in error, please call again" announced a female recorded voice, before I heard the dial tone.
On second attempt, I pushed buttons at random until I was rerouted to a customer service representative whose Indian accent was not especially thick and who seemed to be well trained other than answering the phone simply with "Hello? Hello?" until I responded. Once I informed that I do not own a Chase credit card, he did not push me for any more personal information. With office noises in the background, everything seemed relatively legit. It's possible I was rerouted to a legitimate number after having entered "my account number" incorrectly so many times. I suspect this was a "man-in-the-middle" scam to collect account numbers before forwarding calls to Chase Cardmember Services.
Chase cardholders who receives calls from this number: instead use the phone number that comes with your billing statement.