ring back vs ring in

ring back

verb
  • To return a phone call. 

  • To make another phone call to the same person. 

ring in

verb
  • To make a phone call to (this place). 

  • To encircle, to surround in a ring, engirdle. 

  • To celebrate by ringing of bells or as if by ringing of the bells. 

How often have the words ring back and ring in occurred in a corpus of books? (source: Google Ngram Viewer )