These clowns call every month or so. I have the same experience reported by others: the message says something about last chance to lower my credit costs; when you press 1 to talk to them, nothing happens; when you call the number back it is disconnected; reporting to the do not call seems to do nothing.
Got this called asked what service they worked for. Was "Credit Service" asked for a website to visit for background information said they don't have permission to give it out. Said if they worked for the company why couldn't they give it out? After awhile of asking they just hung up. Calling the FBI in Florida and reporting to the FCC about this.
Same nonsense about "last chance" to lower your credit card interest rate, etc. I told the guy he had called a number on the Federal Do Not Call list, and he just ignored me and kept right on talking. Made a complaint to the Do Not Call website.