Ah, here we are: "With Aquila, we've designed a new aircraft architecture, one that can support staying in the air for months at a time. Aquila is solar powered, and when launched, it will create a 50-km communications radius for up to 90 days, beaming a signal down to the people in that area. This signal will be received by small towers and dishes that will then convert it into a Wi-Fi or LTE network that people can connect to with their cellphones and smartphones."
https://code.facebook.com/posts/993520160679028/building-communications-networks-in-the-stratosphere/ In other words, the airplane replaces the infrastructure between towers, and it also allows for smaller towers. Probably cheaper ones too. It says they want to reduce communication costs by an order of magnitude. - Jed
