It appears the telephone number 866-449-1521 is being used by scammers pretending to be JPMorgan Chase. Therefore, if you are asked to call the same telephone number or receive a text or call from it, please contact JPMorgan Chase directly using the contact information on their website at www.jpmorganchase.com to verify.
I will update this post when I get more information. If you have any information about 8664491521, please share in a comment below.