Who called from 3024429500

Just started to get calls from this number.  They don't leave a message.  How do I make it stop?

CALL WITH NOBODY ANSWERING ON THE OTHER END...

i think its a fax number i was suppose to get a call from aig for auto insurance it might of been them

annoying,and harassing; using up my minutes.

If you call the number back, it will answer as 21st Century.  I had been doing online Auto Ins quotes and 21st Century was one of them.  But it is very annoying to answer the phone and have no one there.  Therefore, I will not ever do business with 21st Century.