The number listed as a missed call

I noticed a missed call." Mrs. James" from "ics incorporated" had left a message regarding some business opportunities. Since the call was for my friend who visited me from EU couple of months ago, I knew this was suspicious. The lady claimed my friend gave my phone number to find out some business opportinities. It is bs because the only place my phone number was used in connection with her name was at northwestern memorial hospital, where she had a doctors appoitment (which was made by me - hence my phone number). As a recent identity theft victim I am upset with the hospital that gives out such info to unrelated parties.
Since I confessed it is me not my friend calling them back, she refused to disclose what is this phone call regarding to.

On my call ID this call always comes up as all zeros (000-000-0000).  A recorded message was finally left with the contact # 708-263-2408 and stated something about a debt.  I called it back late (10:30 at night) because I just wanted to know if it is legit.  The automated system asked me to input the number I was calling from and the account number that was left for me.  However, when it asked for the last four digits of my SSN, I hung up.

I might call it tomorrow, 1/15/08, just to see what the hell this is and to tell them to take me off their list.  I know what my debts are right now, so I have no idea what this is about.

They are a collection agency who does business with Northwestern Hospital.  I was disputing a change and have refused to pay it; they referred the account to this collection agency.  She can call all she wants - I won;t ever answer a call from 000-000-0000 - or call back anyone who leaves misleading messages.