I don't want to sound dumb but how do you do that?

type in reverse search in google
and when you enter the number the provider will be listed

Then I googled the provider and called...

I'll let you know if it works.. so far so good

several calls from the number. try to call back get message saying it's a number out of service.

My daughter has received several calls on her cell phone from this number.  She is 12 years old and the call has come during school hours.  No message is ever left on voicemail.  Returning the call gets the "not in service" message.  We've added her to the do-not-call list.

she said she was calling from sprint.
I have verizon and ask her not to call