this number shows up as only calling in from Lincoln NE, and when I answer they hang up.   I call the number back and the recording says "the number you have dialed is not in service, please check the number and try again"

Didn't recognize number so didn't answer.  Caller left message saying he wanted to set up delivery for a "personal medical alert system....and $3,000 in grocery discounts..."  He said the "system has already been paid for" -- "shipping has already been paid for..."  We have never ordered anything like this and can only surmise it's a scam of some sort.  A return call to that number revealed the number has been disconnected.