repeated calls and threats

I continually get calls on my cell from 201-490-4354 saying they have a message for my son because his social security number is under investigation. I am interpreting this as ""we want to steal his number".   They also say that a collecting company hired them and they are calling from a law office. The messages always have people on the other end with foreign accents and there are many background noises.

When I finally called back and demanded to know who is always calling, the person kept saying "James".  Finally, after I kept insisting, he told me that the name of the outfit is the American Law Division. He then put me on hold and never came back.  I could hear a lot of chatter in the background, as if the room was full of people making calls.

This is clearly a scam and a persistant one at that.