GoTenna creates a cell network out of thin air anywhere on Earth.GoTenna is a pocket-size communication tool that lets smartphones talk to one another without cell service

The Brooklyn-based startup is offering a solution for off-the-grid travelers who need low-cost connectivity for their smartphone -- and it doesn't rely on satellites.

GoTenna is a pocket-size communication tool that lets smartphones talk to one another without cell service

Our modern, wired society often romanticizes going off the grid. Pack-toting hikers bravely venture into areas without electricity or -- gasp! -- cell service, unfortunately inhibiting the posting of that picture-perfect Instagram shot.

While few discount the benefits of unplugging now and again, it's not necessarily safe to trek miles into the wilderness without a backup plan -- or for that matter to live even in urban areas potentially crippled by a natural disaster. That's why people often shell out anywhere from $500 to $1,500 for a trusty Globalstar or Iridium satellite phone.

GoTenna, a Brooklyn-based hardware startup, has a modified, smartphone app-based approach to staying in touch at a lower cost when cell service is shaky, no satellite connection required. The device, a thin 2-ounce wand that can be strapped to a backpack or belt loop, connects to a smartphone app via Bluetooth low energy (LE). Slide out the antenna and power on the device and you'll then be able to send messages and GPS coordinates from your smartphone to others connected to a GoTenna. The company offers downloadable, high-resolution offline maps for referencing transmitted location data.

GoTenna doesn't give your smartphone LTE-style data, so no Twitter scrolling or Facebook browsing. What it does is create a low-frequency radio wave network for its iOS and Android app that can last around 1 mile in skyscraper-filled urban areas, but up to 9 miles in most outdoor situations like hiking and camping. If you're climbing or, say, out skiing, it shoots from 9 miles to as high as 50 miles once you start ascending to higher elevations.

GoTenna is 5.8 inches in length and weighs 2 ounces. When the antenna is extended, which is required for use, the length extends by 2.2 inches.

"That's just the science of radio waves. We are operating at the limits of physics," said GoTenna co-founder and CEO Daniela Perdomo. "If the Earth was curved a different way, you could get more miles than that."

The idea is to allow text messaging both between fellow off-the-gird participants and someone located within the net of reliable cell service in the case of an emergency. There's also a function, called Shout, that lets you transmit information to any GoTenna devices in range. Messages are end-to-end encrypted and not stored anywhere. They also can be set to self-destruct once the recipient reads it.

"You get delivery confirmation," Perdomo said. "Unlike walkie-talkies where you send something out into the void, there's no guess work here." Bridging the gap between WhatsApp and a satellite phone is the point.

"The experience of using this should be the same as a messaging app on your smartphone," she said, though it comes with a bit more juice. A GoTenna can last up to a year and a half on a single charge if it remains off, and its lithium-ion battery will last for 72 hours of occasional use, Perdomo said.

GoTenna is taking preorders starting Thursday. For $149, you get a pair of devices. Following the first batch of sales up to $50,000, GoTenna plans to raise the price to $299 per pair.