This number just called me too. I don't answer phone numbers I don't recognize and they didn't leave a message. Not sure who it is. I haven't tried calling back yet.
I got a call this morning and they did say that I am eligible to reduce my credit card interest rate. They never mentioned a bank name or card they were talking about so I hung up and blocked the number.
They called me to let me know I was eligible to reduce the interest rate on my credit card. They asked "You have a Mastercard, don't you?" I said "No I do not, what name do you have associated with this phone number?" They immediately hung up, and when I called back, I got a recording that this number was no longer in service. And no, I really do not have a credit card.