A mobile phone can be a fantastic resource in an emergency, but what good is it without signal? IBM and The Weather Company are trying to tackle this problem using a technology known as mesh networking. An update to The Weather Company’s Android app uses phones’ built-in radios to send alerts about natural disasters and extreme weather from device to device — getting the message out, even when there’s no signal.

The mesh networking update will be rolling out to The Weather Company users in emerging markets in Asia, Africa, and Latin America. (You can see a full list of countries here.) That’s because it’s in these areas that traditional mobile networks are most congested, and in danger of becoming unusable during emergencies. The update to app has been optimized to be as data-light as possible, but it still has its limitations. For example, phones need to be within a few hundred feet of one another to share information. That means that people in isolated areas won’t be able to take advantage of the app, but it will be perfect for sending alerts to large crowds.

And for those people that mesh networking is able to reach, the alert could be the difference between life or death. IBM says that although other companies like Facebook and Google are experimenting with drones and balloons to spread mobile signal, it prefers to work with a tool that’s already in everyone’s pocket: the smartphone.