Who called from 8133983705

Started getting calls from this number on may 29th 2012.  I say hello but the phone is silent then hangs up.  I called back and it says "thank you for calling customer service, please leave message".  I can't leave message because the message box is full.

Received a call at 11am Sat Morning. No message left...

They called again.  I simply answer, sit there and say nothing.  Neither do they.

813-398-3705 How do I stop them from calling me.  They call every night.  Can't I sue them?

Received a call from 813-398-3705.They call every night.How do I stop them from calling me?