I keep getting calls from this number and they never say anything. What's their problem?

A rude man with a foreign accent called regarding converting to solar energy and proceeded to ask me how much my power bills were per month.  Told him not interested and that we were on the do not call list.  He said he gave a wrong number on purpose, so that I can't report him on the do not call list.  The number that showed up on the caller id was 714-716-4340, with an unknown caller name.

I picked up and no one answered.  Just dead air.