i guess they did leave a message - here is most of the text of the voicemail.
"hey guys this is Kerry Green here, um we spoke on the phone last week on possibly trying to lower your interest rates and trying to reduce your payments on your credit card...
and since you are only making the minimum payments this could be a great opportunity for you ...
this will be my last courtesy call 1-877-723-1429 that is a toll free number (repeat number) and I will be in the office until 10pm eastern"
telemarketing spam call, i've never asked anyone about lowering my credit card payments. probably since i don't have any
Based on the pattern from these posts, I would guess that its a scam service that just says "uh hi" when you answer, but leaves the "advertisement" when it goes to voicemail.