There's a cell tower a couple miles away but there's hills in between us and it. We can drive 1/4 mile up the road to the top of the another hill and get one tiny bar, sometimes. Just enough to send and receive texts but phone calls, not so much as the signal is intermittent. 5G, 9G, won't help if it's still intermittent.
Replace your terrain with skyscapers. The phones work fine. How could that be? Of course, infastructure is why that stuff works in cities. A receiver on on the hill top of the hill east of you would do the trick. No one has designed an affordable application for your situation. But, it can be done. The lack of TV signals in mountain areas was how the cable industry got started. The first guy who decided that it was a good idea is a multi millionaire. He is still alive.