That's true, but if you are a loner like Ennis, and low on cash, you can live without the phone. He wouldn't a called no one but his daughters and Jack. On the other hand, I don't think Ennis wanted one, because I am convinced if heard Jack's voice he would be a total wreck. It was easier to be detached from Jack that way. I think it tore Ennis up each time to see Jack as much as it was for Jack to see Ennis.
The fish were not jumping as much as Ennis and Jack and their hearts.