Caller ID showed "US POSTAL SVC."  Don't know why they'd be calling me from the 404 area code (Georgia).  Nobody on the line, I suspect a scam of some sort.

USPS calling to introduce me to new postal services.

In my case, the caller truly was someone at the US Postal service. On my phone, the call did not show an identifiable caller ID (maybe it said WIRELESS CALLER -- I forget), so I ignored the call and looked up the calling number on 800Notes. When I saw the postings, and because I was expecting a call back from the postal service to resolve a problem, I called them back, giving them my case number to reconnect to the right person. Legit.
(Of course, scammers can always spoof the number.)
NOTE: 800 Notes needs another Call Type choice, like Legitimate Caller.

Since CID said it was from the US Postal Service, I answered.  On the other end was a lady who sounded Asian (China, maybe?).    She asked me if she had reached a business or residence.  When I told her it was a residence, she apologized and said she would remove my number from their calling list, and that was the extent of the call.