This is a collection agency working to collect on AT&T past due mobile accounts.

saying i'm past due when i cancelled service months ago, am happy with my TMobile service now. Had the audacity to call my cellphone.

keeps calling our home asking for our son saying is very important

I also got a phone call from this number and a guy stating it was imperitive that I call him back.  He gave an account number the call was referring to, and said the matter was time sensitive-scam!

I received a call from this number, the guy didn't say who he was working for but said it was imperative that I return his call.  I'm guessing it's a scam of some sorts, if it was something important, he'd say who he was representing or working for.