Who called from 3305499026

We're on the national Do Not Call Registry, and we get calls from this number all the time. When we pick up the phone, there's no one there. What's the point of their calling us all the time when they never say anything?

This number shows up on my caller ID daily. Never a message left. On Sat. 2/23 I was home and picked up. They hung up.

I receive calls at a minimum 10 times a week, usually during the day but  they have called in the evening.  It registers on my caller ID as a "private caller" so I don't answer. Any suggestions how to block a private call?

This number has shown up on my caller ID several times in the past two weeks.  When the call is answered no one is there.

Every morning, rings, nobody there. If it is the red cross I am done donating forever..