Rather than focus on the phone, could you look into getting a femto cell installed? In my country some of our providers support these and you can buy/install t

Rather than focus on the phone, could you look into getting a femto cell installed? In my country some of our providers support these and you can buy/install them legally. You could contact your networks to see if they support this. https://en.wikipedia.org/wiki/Femtocell https://en.wikipedia.org/wiki/Femtocell I had an old Nokia candy bar that used to get great reception. If he's just making calls this could be good, plus in a low reception environment batteries drain quickly too so the candybar would be suitable.