I called the number back. Got an automated message telling me that I had reached a non-working number and then gave some kind of message ID and then it hung up. I just blocked the number on my phone. Problem solved.
You don't want to identify who you are or leave a message? Then I guess you really don't want (or need) to talk to me. ;-)
They call several times a day. When I ask who's calling, thet hang up. Several times they said they are calling about diabetic equipment. They don't take "no" for an answer.