Zello has become a popular app in the wake of Hurricanes Harvey and Irma, shooting to the number one spot on iTunes.

The app has gained popularity for its ability to connect with people without phone numbers. Many volunteers and first responders on the scene after Hurricane Harvey in Texas used it to connect with people who needed to be rescued.

As awesome as this app already sounds, there is a catch: the Zello app cannot function without cellular data service or an available Internet connection on your cell phone.

As much of a handy tool as Zello's app may seem, it is best to be fully prepared in the case that wifi or cellular data is not available.

How it works

Once users create an account, they explore a variety of channels to join and chat. In the case of Harvey rescue efforts, channels such as the Cajun Navy Dispatch and Harvey Animal Rescue appeared where users could quickly push a button to talk and seek help.

There is some potential for confusion as users parse which channels are linked to official rescue groups. Recently, a channel for Texas Search and Rescue was pulled after the official group claimed their logo and name were misused, said Moore.

The technology for Zello dates back to 2007, and saw boosts in use during global uprisings, including ones in Egypt and the Ukraine, as well as protests in Venezuela. Zello was blocked during several of these events, most recently in Russia in April.

For more information, check out our news partners at the Tampa Bay Times.

Other Apps

In addition to Zello, here are some other apps that can be essential when you're in the path of a major storm.

  • Red Cross apps: The Red Cross has several disaster-related apps that allow you to monitor weather alerts, and notify loved ones you're safe. The different apps include an all-inclusive "Emergency" app as well as apps specific to tornadoes, hurricanes, and earthquakes.
  • WhatsApp: One of the most popular messaging apps, you can use WhatsApp to leverage your phone contacts, so you add friends, family and other people as you would any contact on your device. Messages are encrypted end to end, which means only the sender and recipient can see them. You can also use it to make voice and video calls, not just text messaging.

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USA TODAY contributed to this report