Who called from 5123668582

Just got a call from phone number 512-366-8582. He asked if (my name) is there, I said yes and the call hung up on me.

Asked for "Ryan." When I said he had the wrong number, said "Maybe you could help me. I'm from donor relations..." at which point I hung up. Block.

Called my cell. Did not reply. No message left. ROBO?

See this # calls my phone and hangs up before I can even answer. It rings once and then it's gone

I answer him and he hung up. Call the number back it was busy.