I got one today, rude s.o.a.b.who are these people?

I received 2 calls from this number 215-821-9079.
The phone only rang once each time.
2nd call was less than 1 minute after the 1st.

No clue who called from this number, no reply

Got a call, no words, no sounds no background noise nothing.  Getting a few of these now-a-days some without any numbers.  Any ideas what's going on?

Called my cell phone as well and left no message. How can I stop them?