Did not say who it was.   When I called back they did not identify the company.  So it must be a collection company of some kind.  No message was left on my voicemail.  And having been out of work for a couple of months, I am a little behind on a few things.   My guess is that it is Apria Healthcare.   They tend to come up from the local area.    But I was not going to start asking questions to find out.   Glad to be working again though so I can get caught up on things.