I use caller ID to screen calls prior to answering,  If I don't recognize number, or caller does not leave a message on answering machine - they do not get to talk to anyone in our household

I received a call from this number tonight.  They (male voice) asked for me in person.  When I told them this was me and
then asked them who was calling, they hung up.  I tried a couple times to call back, phone always busy.  I called the number again, no answer.  Caller id said call was coming from Newark, Delaware.

Who is making these phone calls and for what reason ?

Called but left no message.