He learns that Mr. Harrigan had lost his mother very early in life as well, just like Craig.
The teenager also now knows that the mysterious texts he got from the number were really Mr. Harrigan's way of telling Craig to stop talking to him.
Either Mr. Harrigan was getting wounded because he couldn't rest soundly because of these reaches, or he didn't want Craig to get injured since the little child was getting angry and vengeful, which would damage him in the long term.
Craig says sorry to his former boss and his mother at the cemetery where they are both buried.
He then runs to the edge of a lake and throws his old phone, which was the only way he and Mr. Harrigan could talk to each other, into the water. This ends their strange conversations for good.
He also wants to get rid of his current phone, but he can't because smartphones are such an important part of modern life.
In a different background story, Craig says that he doesn't want to be buried with his personal phone.
Some people might find "Mr. Harrigan's Phone" interesting to watch around Halloween because of the supernatural suspense in the beginning, but it wouldn't hurt to skip this movie.