I also got the 631 calls for about 2 months. Now getting these calls about 6-8 times a day. I heard the best thing to do is not to answer, because once you do It's known as an active line and your number just keeps getting passed around. Then again, it looks like not answering isn't stopping them either.
I got a call from this no. on my cell phone. Interesting as I just read this because I actually live in a 631 area code. It is the Eastern half of Long Island, where Optimum/Cablevision is.