What should i do about this?

Okay so i am a 13 year old male and lately my house has been getting calls from some guy. The guy said his name was daniel and he wanted to speak with my mom and he knew her name too. I always say oh shes not here right now and he says ok and hangs up. He only calls when my mom is gona from th house but its not that much of a coinicidence because he only called 3 times. My mom said she doesnt know a daniel and that she wants to speak to him if he calls again. And today when my mom was out he called again and both me and my sister picked up and said hi and he said hi its daniel and is donna there? I said no but my sister hung up and when she did that he screamed "Please dont hang up on me!" then he hung up. I called the number back and the first time it went to a fax machine and the second time (but was still the same #) it said this message box is full and cannot hold anymore messages. So im really worried im home alone and when i looked outside i saw a white van stopping in front of my house and two guys going into my nieghbors house (my neighbor was home of course) so nvm that but what should i do. and if you could what area code is 1602 because thats the area code. please!