Last fall hundreds of thousands of pro-democracy protesters took to the streets of Hong Kong and encountered a serious logistical issue: Their phones weren’t working. The sheer number of people concentrated in the area crushed the network, crippling their main form of communication. At a time when staying in touch was critical, it became impossible.

And then something interesting happened. People began chatting with each other, but not over Wi-Fi or data networks. It was via FireChat, a new app from the company Open Garden. FireChat, like the similar Serval Project, builds mesh networks by connecting smartphones via the device's Bluetooth or peer-to-peer Wi-Fi. This effectively turns every smartphone with FireChat into a node that can carry and deliver text messages. The big idea is that instead of relying on a centralized ISP or telecom company to provide service, people are able to build their own decentralized network that can grow as large as there are people who have the app downloaded. In the case of FireChat, these messages end up in either a massive group chat or can be encrypted and delivered as a private message by hopping from phone to phone until it reaches its intended recipient. “In a sense it’s like a blind postman,” says Christophe Daligault, Open Garden’s chief marketing officer.

Since the app launched in the spring of 2014, it’s been used in Hong Kong, Iraq, France, and Ecuador during major protests and natural disasters (more than 500,000 people downloaded the app over the course of a couple days in Hong Kong). It’s also, we should note, wildly popular with the Burning Man set. As of today, though, FireChat is attempting to organize its biggest network yet. The company just announced it’s partnering with Marikina, a city of 400,000 that makes up metro Manila in the Philippines, to build a city-wide mesh network that can be used during natural disasters.

The Philippines, which gets hit with an average of 20 typhoons a year and is situated along the Pacific ring of fire, is a natural disaster hotspot, making it a perfect test bed for the app. "No one in the Philippines has forgotten typhoons Ondoy and Yolanda, we need all the help we can to be ready,” says Marikina’s vice mayor, Jose Fabian Cadiz. “We need a way to share critical, live information in real time, at a very large scale - even if all networks are down." At one point during typhoon Ondoy, 80 percent of Marikina City was submerged in water. Many residents were stranded on top of their roofs with few ways to call for help, because the networks were down. Cadiz believes implementing city-wide system like FireChat could have saved lives by making it easier for people in danger to reach out to city officials.

FireChat

Building a City-Wide Daisy Chain

FireChat’s effectiveness hinges on density. The app's mesh network is only as strong as the community makes it—the more people on the network, the more stable it is. FireChat works on phones as long as they're less than 200 feet apart, but in times when the density is spotty, the company will use a GreenStone, a little plastic module that stores messages and uses Bluetooth to extend the network. This GreenStone bolsters the network and stores messages until someone with FireChat comes into range and can pick up those messages.

Density is less of an issue in Marikina, where population density can reach 50,000 people per square mile (that’s twice that of NYC). Daligault says typically five percent of the population would need to have FireChat downloaded in order for it to work well. The exact timing also depends on how those people are distributed throughout the population; but Daligault says that if someone were to send a message from one side of Marikina to the next, it would take anywhere from 10 to 20 minutes to reach its destination. That number might be even less in a city like Marikina, where people live in closer proximity to one another.

Relying on other people to relay your message isn't always efficient, but it is effective. In a situation where FireChat is used as a secondary option to traditional networks, good enough really is good enough. After all, something is better than nothing. Open Garden's CEO has expressed plans to eventually build FireChat into a totally free mobile carrier that could replace your paid phone service, but getting to that point might take a while. “I don’t know when we’ll cross the chasm so that this technology will become ubiquitous enough that everyone can benefit from it,” says Daligault. In other words, it’s going to take a lot more downloads before FireChat becomes a feasible way for the average person to reliably communicate.

And for now, that's fine. The initiative in Marikina is the first time FireChat has partnered with the government, which is notable because the app has traditionally been used to subvert government control. The company says if all goes well, they'd like to roll it out to all of Manila and eventually all of the Philippines. As Daligault puts it: “This is a test run—a big one."