This is a weird one. A recording claimed to have a call for "this number". It seemed to be unable to connect on the other end, which makes no sense.
It seems someone wants to verify a call can be placed to a number or is checking on whether someone is home, but I still get calls for the previous owner almost a year later & that person was not at my address.
This really is an Unknown but that's my best guess.
No message, appears to be something more than a wrong number. If I get this number again, I'll just block it, like I do for all these telemarketers and collections people. If you don't leave a message I don't want to talk to you.