After Esther suffocates Daniel in the hospital, Kate slaps Esther in the face. The hospital staff then hold down Kate and she drops her iPhone, screen down. The iPhone starts ringing, even though the screen is facing the floor. In the next scene, it is still ringing, but with the screen facing upwards.
When Kate shouts "I'm not your f*****g mommy" to Esther, this is the same final dialogue of interaction between the antagonist and protagonist as in "The Ring 2".