The make/model of the cell phone can make a big difference in reception.

For many years a friend kept an otherwise obsolete 'brick' phone with a traditional handset because it had several times the signal strength on transmit over more compact units and it easily accommodated switching to a large external antenna to pick up distant cell towers. He did this because a lot of his work was in rural areas where cell coverage was spotty.

Given enough transmit power and sufficient antenna size he was able to maintain good service in normal times, and jump over gaps when cell/s went down due to storm damage.

Cell service providers usually have technical staff on hand, over and above the sales staff that usually know very little, that can recommend suitable phones, ones that have an external antenna connector, and compatible antennas. They should be quite familiar with the issue and have answers.