the exchange looked odd to me but no one was on the line when I answered

I saw "Name Unavailable" but a phone number for the incoming call. The caller asked to speak to whoever is responsible for paying the utility bill. I hung up and then redialed the phone number 210-034-1836. Got a recording, "Due to phone company problems, we are unable to complete your call."
Uh huh...can you say scam?

Repeated calls from this number.  No one on line when I pick up.  I'm on 'do not call register' and it worked for about a year and is now becoming ineffective apparently because of ease of changing cell phones.