As mark7914 said, if the carrier doesn't have a tower near the "rural area", no cellphone is going to wok miracles. And if there's one house per dozen acres, it doesn't pay for them to build a tower in the area - it would take them decades to pay it back. If you can get a signal standing on the roof, a micro cell mounted on the roof might help. But if there's no signal at all, aside from a really high-gain passive repeater - two antennas, a high gain one aimed at the tower, a little omni inside the house, connected by cable. Maybe. If there isn't even enough signal for a high-gain antenna to pick up, and you don't have WiFi calling, there's nothing you can do.