Caller ID displayed as "Unknown name", following by an unrecognizable number. I let it go to my answering machine to screen the call. They didn't leave a message. I dialed back the number and encountered a female voice recording that said "We're sorry. The number you dialed is not a working number. Please consult your directory and dial again." Afterwards, the line went silent but it didn't automatically disconnect. I then decided to hang up.