If you keep getting a call from an 800 number and you do not know who it is because they are not leaving a message or a call back number you could try using the reverse look up.
Or you could have the phone numbers that keep repeatedly calling you like this removed by putting your number of the National Do Not Call List database.
This type of site can help you to be removed those annoying calls.
It gets you on a do not call list that the registered company or persons with those 800 numbers won't be able to keep calling and annoying you now.
Maybe you have a call that keeps coming in from an unknown number or area code to you? You could try reverse look up to see if there is more information available on that phone number which keeps calling you.
With the Internet you can now find these things out.
There are public records websites where you do not have to sit back and just listen to your phone ring for no real reason.
They could be a telemarketer or a "wrong number" hang up.
There are many times that a caller will call your cell phone or landline and not get you on the line.
So they will simply hang up after your phone puts them through to voice mail.
Maybe you do not know the caller so you want to wait until the call goes to voice mail and then listen and screen the call right back to them? How can you do that if they do not leave a message and you are unaware of who they are? Finding reverse phone number online could help you out.
It will allow you to find out information about the number that is calling your phone number.
This could give you the opportunity to either call the number back or let them know that you are not interested in speaking with them.
Or, it could very well be someone that you want to speak with, but just did not recognize their number.