While I was out I received call from this number--name "unknown."   I am wondering whether this is a high scam number, and
have not returned the call
.

"UNKNOWN " robocall saying I, as a "Gas South customer will have my service cut off if I do not pay immediately.  I have not used Gas South in 4 years and they do not show a balance due.  Since the phone #  to pay with is linked to Western Union, I wonder if this isn't a SCAM and I would be giving them my credit card number, name, address, etc.  Can't prove it, just a suspiscion.  Why wouldn't Gas South use their own name?  

My caller ID just said Griffin, GA.  They have called several times.  This time I answered, but no one spoke.

no one on the other end of call when i answered...

I've received several calls from this number. I never answer and they don't leave voicemail. I just added them to my blocked callers.