goTenna

goTenna enables you to communicate without any need for central connectivity whatsoever—no cell towers, no wifi, no satellites—so when you're off-grid you can remain connected. In fact, goTenna will even work if your smartphone is in “Airplane Mode”! 

How does this magic work?
Pair your smartphone to your goTenna device wirelessly, using Bluetooth-LE. Your goTenna needs to be within 20 feet of your phone, so that the two can communicate with each other. Use our free app to type out a text message or share a location. Your smartphone will send the message to your goTenna, which will then shoot it out, via long-range radio waves (151-154 MHz), to the intended goTenna(s).
At the other end, the exact same thing happens, in reverse: the recipient goTenna sends your message over Bluetooth-LE to the smartphone app it's paired with. All of this happens in a matter of milliseconds, and your goTenna will be able to transmit to any goTenna within range.

What kind of range can you expect?
The most important thing to understand about range with goTenna is that it is greatly dependent on your geography: specifically your terrain and elevation.
Next, there are two distinct ways to answer this question.

What is the theoretical range?
The first approach is to use industry-standard radio-frequency propagation calculators that assume ideal conditions.

What is the more likely range?
When you don't find yourself at the edge of cliff or hanging out in a skyscraper, your range with goTenna will be smaller. Most of the time you'll probably be trucking your boots through the dirt with land (or water) all around and level with you, and the goTennas you and your friends are using to communicate with are probably going to be 4-6 feet off the ground.

So your range with goTenna will look more like this in those more common scenarios:
City street to city street: 0.5-1 mile
Forest to forest: 2-3 miles
Water to water: 4-6 miles
Desert to desert: 4-6 miles
 Can you get more than this when you're on the ground? Absolutely. We wouldn't be surprised if you did a lot better. But we want to be the first honest radio company, so we'd rather under-promise and over-deliver.

How can you improve your range?
As you probably get by now, elevating the goTenna increases its range drastically. Hike up a little, hang it from a tree, etc. But another way to improve your range when you can't elevate yourself significantly—or even when you can—is to attach it externally to other gear (e.g. a backpack), as opposed to having it at the bottom of a bag. That's what the nylon attachment strap is for!

Key app features
Send & receive text messages for free
Share locations on detailed offline maps
Instantaneous transmission within range
Automatic message retry & delivery confirmation
Individual & group messaging
”Shout” broadcasts to anyone within range
Proximal friend map & location pinging
Emergency chat
End-to-end encryption (RSA-1024) & self-destructing messages
Compatible with iOS & Android

Key hardware specs
Antenna
2-watt radio
Flash memory good for 1000’s of messages
Rechargeable Lithium-ion battery
Micro-USB connector
BluetoothLE data interface
Status indicator lights
Nylon attachment strap
Water-resistant
Dust-tight