at fault vs wrong number

at fault

prep
  • guilty, responsible, to blame. 

  • Of hunting dogs: unable to find the scent. 

wrong number

noun
  • A telephone number dialled by mistake, for example by transposing digits. 

  • A telephone call received from an unfamiliar caller, due to a mistake in the number dialled. 

How often have the words at fault and wrong number occurred in a corpus of books? (source: Google Ngram Viewer )