Coolidge liked the dignity of the presidency. He didn't get on the phone easily. It's possible that he banished the phone from his desk. He was known to use it from time to time. The person who was hilarious with the phone was Hoover. He was a real engineer. He made a closed circuit phone where he could call the important people and they could call him, a government hotline, but it was closed. He shut out the possibility of input from people he didn't expect to get input from.