I get these calls from many differnt numbers but don't answer them (based on the area code they are calling from). I get as many as 10-15 per week but don't know who they are from because I don't answer them. I believe these are automated calls to detemine if your number is available for a call from a telemarketer. That is why it hangs up when you answer it. If you do answer it, then an acutal person starts calling.