None.  These scammer debt collectors rely  on fear and threats.  They rarely, if ever, go  to court.  In order to go to court they would have to associate with an attorney licensed to practice in your state.   In that instance you would receive a letter from the attorney for the other side.  There would be a paper trail. You would NOT have first heard about a civil case from some scammery-scummery debt collector who cold calls you and demands money.  If a case were filed, then you'd have to be served with process by a process server licensed to serve process in your state or locality.  This group is located in California.  If they have a valid debt aainst you demand that htey send you a debt validation letter by US mail.  E-miail no good.  Of course they won't do this, so simply ingore and block the calls.