SEMINOLE COUNTY, Fla. (WOFL FOX 35) - It's the app everyone is talking about: Zello. It works just like a walkie-talkie, and it's been credited with helping in Harvey rescues, but there's one problem says Tech Expert Tom Jelneck
"If there's no internet and there's no cellular, it's worthless. You can't use it."
The app has clarified on their Facebook page, "If there is no WiFi and no cellular data service, communication apps (including Zello) WON'T WORK."
The good news is Comcast has opened up its hot spots across the state, but experts warn you to be mindful of using an unsecured, public WiFi.
"I would really encourage people not to be doing financial transactions, not to be logging into accounts, because the safety of that WiFi could be potentially - there's jerks that look for opportunity," Jelneck tells FOX 35.
If cell towers do go down, but there's still wifi, both Android and iPhone users can enable calling over WiFi.
"Lets say that your cellular gets compromised, you can actually still make phone calls over your WiFi provided you have a pretty high quality signal," Jelneck explains.
When networks are still working, emergency management officials say it's best to send a text, instead of making a phone call. It puts the least stress on an already busy network.
"It's just a quick flash of data, so the system can handle a lot more text messages, than it can phone calls," says Stephen Watts, Director for Emergency Management in Osceola County.
More shelter locations will be announced Saturday.