I've been getting calls from this people, too. I got the March issue of Consumer Reports today, and they suggest reporting these numbers from "robocallers" to the FTC via the Do Not Call Registry. They claim that the information goes into a database that can help regulators identify the sources of illegal robocalls.
This is the collections department of Credit One Bank. They never leave messages. They are the credit card company that sends you 2-3 credit card offers EACH WEEK. The ones with zero interest, zero payments for 90 days and all kinds of other perks.
One of my offers was stolen, activated and charged. I am responsible for the charges unless I report the card lost or stolen. I'm currently waiting for the Fraud Dept. to call me back so I can officially report it stolen.
These people need to be put out of business. Credit card offers like this are ID theft.