Incoming number was 406-351-4172. Voice was a younger female identifying herself as Madison Smith, though I'm sure the name and voice can change. Given the descriptions above, this was the same message other people are getting:
"Uh, Hi guys, this is Madison Smith giving you a call back. Um, we spoke last week on the phone about possibly trying to lower your interest rates and reduce your monthly payments on your credit cards. Um, I wanted to let you know that I did find a solution here. We've got a program that can lower those rates to as low as 1.5% and possibly cut your monthly payments in half. And, since you were only making the minimum payments this should be a great opportunity here for you. Um, this will be my last courtesy call so please give me a ring back today at 1-800-310-2148. Again, you can reach me toll-free here at 1-800-310-2148."
Agree with above that this is likely a phishing scam.