This is likely a scam. You should ignore the calls and ask your phone company to block the number. Do not give any of your personal information to the collector. Most of the scams I've seen deal with people that have taken out payday loans in the past. You should file a complaint with the Federal Trade Commission, too, at www.ftc.gov. Ask your supervisor to be patient with you, as you have no control over a collection agency that is likely a scam.
Information on Avvo should not be construed as legal advice, as each case is different. For information about your specific case, please contact a consumer law attorney, or contact me at www.agrusslawfirm.com
Instead of pursuing a strategy that doesn't work, find out everything you can about the caller - name, phone number, address. Ask if they have a local license to collect and when they lie and say they do, ask for the license number. Ask if it is okay for you to record the call. Then wait for them to hang up on you.
Hope this perspective helps!