During Hurricane Katrina, 70% of cell phone towers in the disaster area went down, leaving millions of people unable to contact their loved ones.

To make matters worse, even some folks who evacuated before the storm hit were unable to call their family from their cell phones because the towers were down in the specific area code that their phone number was tied to.

For example, Gary M. was unable to dial the cell phones of his daughter or her boyfriend for days after the storm hit even though they had evacuated from New Orleans and were driving west through Texas away from the storm.

The problem revolved around basic network architecture. When cell users take their phones outside their local area code, the wireless network checks back with a network computer in the home market to verify account information and let the service provider know where to route calls.

In other words, when the communications to the home switch in New Orleans and nearby area codes was cut off by the storm, cellular operators quickly realized many people that had evacuated ahead of the storm were still unable to receive calls on their cell phone.

The thing was, incoming calls present a different problem because the phone network can’t determine where to route those calls without first checking in with the New Orleans switch to find out where the cell user is located.

Hurricane Katrina wasn’t the first time we’ve seen widespread cell phone disruption and it surely won’t be the last.

Anyone who was living on the East Coast during the 9/11 attacks will remember that many cell phone companies were experiencing double their normal call volume and networks simply couldn’t handle the added calls and failed. (I was living in Virginia at the time and tried to call my parents, but no calls would go through.)

Of course, communicating during a disaster is something I’ve talked about before, but now I want to share with you some secure communication methods.

During a disaster, communication such as HAM radio, two-way radio, CB radio, and other methods can be lifesaving, but the problem is, they aren’t secure, meaning anyone can listen in on conversations.

With that being said, here are the top ways to securely communicate when disaster strikes.

Satellite phones. For a lot of emergency situations, satellite phones are a pretty good option. The biggest problem with them though is cost. The advantage to a SAT phone is they work through orbiting satellites instead of cell towers.

In addition, a SAT phones use is not limited to areas covered by cell towers and can be used in almost all geographic locations on the Earth’s surface as long as you have a clear picture of the sky.

If you were considering a SAT phone I would check out a company called Inmarsat. A SAT phone can easily cost $500 and you have to prepay for minutes, but they can save your life if you are stranded.

GoTenna. Anyone who’s been camping knows what a pain it can be to get a cell phone signal out in the middle of nowhere. The GoTenna is an off-the-grid communication device that uses a 2-watt Very High Frequency (VHF) radio to send messages and location data to other users.

That means you and your loved ones can communicate by text and arrange to meet up using your Android or iOS device, without having to depend on cell network connectivity. Now, GoTenna doesn’t offer voice communication, but it allows you to send text messages, even without a cellular connection.

In addition, it offers end to end encryption if both parties are using the GoTenna app. A pair of GoTenna devices sells for $160 on Amazon and they attach to your smartphone, so it’s a much cheaper option than a satellite phone.

Signal App. Signal is a free application for your Android or iOS phone that provides secure voice calling, texts, and video calls to other users of Signal. The thing is, this app does require a connection to a data network or Wi-Fi.

In other words, if the cell tower were down you would need to connect to a Wi-Fi network. Signal messages and calls are always end-to-end encrypted and engineered to keep your communication safe. In fact, even the company who owns and operates the Signal application can’t read your messages or see your calls and no one else can either.

This is a great option for everyday use, as well as emergency use, when you want to keep your conversations private. The reality is, during an emergency many people will rely on two-way radios and HAM radios to contact their loves ones.

While there is nothing wrong with this, you need to be careful with the personal information you share on these radios as there is most likely someone always listening.

The last thing you want to do is tell a family member when and where you will be leaving, essentially giving looters a roadmap to break into your home once you’re gone.