A man from US government said he wanted to give money to me

Forgot to post - I get three different error messages when attempting to call this number back.  All are some sort of "disconnected" or "not in service."

several calls all times of day.  Only once has been there when answered, and the called identified herself as "Apex Services" and then hung up when I asked who she was and why she was calling.

They have called me several times and never answer right away when I say hello.  When they do answer you can hear the noise of a ton of other people talking on phones.  They keep calling looking for someone who had my phone number over two years ago.  My guess is that they are collections.

Caller ID reads O2C, have called several times, when I answer, they are silent, then hang up. Does anyone know who this is?

Says private caller and wont answer.