I've been receiving two calls daily from this number and no one leaves a message.
I took the advice of another poster: call the number back, an automated system identifies itself as NJ Resources, follow thier prompts to be added to the do not call list, you'll press #1 and then #1 again.
Got a call with no message left on 3/30/15. If it is NJR, they recently did my water heater installation, and likely are looking to do a survey on their customer service. They are/were affiliated with NJ Natural Gas, and are not a "spoof" caller.
I received a call today and no one was there, however I left it on while I was Googling the number and about a minute into the call a recording came on to say it was NJ Natural Gas regarding a recent interaction I had with them and they left a number for me to call them back.