one right after the other won't leave a message

Get at least 2 calls a day.  No message

I don't answer, nobody leaves a message. When I called it back a few minutes later it says the number has been disconnected at the customers request. It's obviously some scam.

Yup exaclty what happened to me in that order!!

Do consider maybe getting a call blocking device or phone.. You can google them and many are around $60.00 or so.

Report your callers here, not just to the DNC alone:

https://www.ftccomplaintassistant.gov/#&panel1-1
https://esupport.fcc.gov/ccmsforms/form1088.action
https://complaints.donotcall.gov/complaint/complaintcheck.aspx?panel=2

By State DNC lists:
http://800notes.com/res/DoNotCall.aspx

FCC Abandoned Calls Complaint form:
http://www.fcc.gov/cgb/consumerfacts/1088D-R.pdf
email:  fccinfo@fcc.gov