I got a call from this number many times. Don't know who is that.

Tired to the telemarketing calls that wait for you to stop another call, and when you do to see what it's about - they hang up on you.  I assume it is so you call them back and they can claim you called them.

Phone rings, drop what your doing to answer it, and 20 seconds of silence after you say hello, and they hang up with out a word.  How do they get unlisted numbers with line blocking. Somebody hire a pest cleaner and get rid of these worthless parasites.

Recording with female voice identifies itself as from "Card Member Services." It offers to reduce interest to ~6% on unnamed card. "Do this now, you're running out of time.  Says pressing 9 will connect to a telemarketer. I press 9.  Non-professional male voice answers "This is ....mumble...."  I ask what card this call is about.  Call is ended by telemarketer.  

Can't this call be traced and turned over to law authorities?

I agree with the above calls, call is from Florida but I do not answer, was just curious what others were getting.  I also am on do not call list but this does not seem to deter these calls.  How can you have a 000 telephone prefix??  Take your time and report these calls via donotcall.gov, the same website where you signed up for do not call.  This has stopped these types of calls once they are reported.