Vonage will do it. They charge something like $5 a month for an additional number. I suppose in your case you could just order it with a NJ number though. The number will answer where ever the vonage router is. I took mine to work one day just to try it out. About 10 seconds after plugging it in to a data port the sync was complete and calls to my home phone rang at my desk. I know someone who took his router to Japan with him and was getting his home number calls in Japan.
Now, for answering, it would be nice if you PM’d me your email address and I’ll send you a referal link which gets me 2 months free, and a free month for you.
There are lots of “vonage alternatives” out there now, but few that I’ve seen who will give you that > land line quality and reliability. Not saying the don’t exist, but with vonage I know phone is going to work every day.