called landline - did not answer - no message left

No message left, area code 908 doesn't  inspire hope that it was a one and done.

I answered the phone, no one will respond.  When I call back, all I get is a busy signal

Why do you answer calls you don't recognize?  All you are doing is confirming yours is a live phone number, and you are gullible enough to answer.  Now you'll get even more of these SCAMMER calls.  Busy when you call back because it's a spoofed (not real) number showing on caller ID.

Silent..