Notes

SOS Devices With Two-Way Messaging
Most modern devices are designed to work as standalone SOS beacons, but many also include two-way messaging. Examples include the SPOT Gen4, SPOT X, Garmin inReach Mini, ZOLEO, Somewear Global Hotspot and the Bivy Stick.

Another way to signal SOS is by tapping a window or pipe in Morse code: three fast taps, then one slow, and then three more fast. This is a good choice when you can't speak.
One-Way Satellite Messengers

For the most part, satellite messengers—as opposed to PLBs—require a subscription for use. The fee structures vary widely, but generally you’ll pay an upfront fee for the device itself and then choose a plan that offers varying combinations of messaging options, tracking intervals, and other features.

In a nutshell, satellite messengers offer two-way communication and tracking capabilities that work in tandem with your smartphone (or sometimes independently) when you’re in remote areas without cellular coverage. They also include an SOS button that, when pressed, sends a signal to the private search-and-rescue services (standard bearers are GEOS and Global Rescue) alerting them you’ve activated the device’s emergency feature.

These devices—including the SPOT Gen4, Spot X, Garmin inReach Mini 2, and ZOLEO—relay your location to the GEOS International Emergency Response Coordination Center in Houston, Texas or the National Oceanic and Atmospheric Administration at Tyndall Air Force Base in Florida. You’ll need to provide your name, location, and contact information before a response team can begin coordinating a rescue.

Unlike the PLBs, satellite messengers don’t require cell service to operate and use their own private network for satellite communications. The Spot X, for example, uses the Globalstar satellite network and offers near-global coverage, while Garmin devices, like our review pick, the InReach Mini 2, rely on Iridium satellites to cover all but the most polar regions of the world.
Two-Way Satellite Messengers

Jed brings a level of professionalism and competence to this category that is invaluable. He almost always brings a satellite messenger or personal locator beacon on his outdoor adventures and is one of the first to test any new product that comes to market. Jed's testing is thorough and objective, ensuring the best possible outcome of each review.

If you need help, press the SOS button on a PLB and it will signal a local search and rescue agency via satellite. The agency will dispatch a crew to your location, hopefully within minutes. On-the-ground SAR response time may vary significantly, however, depending on terrain, weather conditions and local fiscal, personnel and political factors.

Most PLBs and satellite messengers are able to send non-emergency messages as well, which helps you stay in contact with friends and family while on backcountry trips. This functionality requires an additional subscription and costs more than emergency messaging, but it's still a great option for anyone who recreates in remote areas or travels abroad.

Some devices offer seamless messaging on both satellite and cell/WiFi, like the Garmin InReach Mini 2 and GPSMAP 67i, ZOLEO, and Global Hotspot. This feature is also available on the new Garmin InReach Explorer+ and SPOT X, though you must pay an extra fee to add it. In our tests, the messaging app on the Global Hotspot and the inReach Mini 2 was noticeably faster than that on the inReach Explorer+, Bivy Stick, and ZOLEO, but this could be due to a number of variables, including device specs and your wireless carrier.
One-Way PLBs

Generally speaking, PLBs (such as our former pick, the Ocean Signal rescueME) and other one-way beacons like the now-discontinued ACR ResQLink 400 and the SPOT Gen4 have just one function: to summon emergency help by sending a distress signal. These devices offer no texting, no two-way communication, no tracking with waypoints, no weather reporting and no ability to connect to social media. They are simple, affordable, nearly indestructible, and have long battery lives.

That being said, they are a critical piece of safety gear for many outdoor enthusiasts. The National Oceanic and Atmospheric Administration requires all PLBs be registered in the United States, which is free of charge. It's worth noting that a distress signal sent by any device will be automatically flagged as such, regardless of whether you meant to press the SOS button or not, so it is crucial that you only use this feature in cases of actual emergencies.

Personal locator If you are looking for a PLB with the ability to communicate in addition to the SOS button, we recommend examining the options available from Garmin, Delorme and Spot. The two-way satellite messengers we've reviewed, including the InReach Mini and X, are more advanced than the simpler one-way devices but still affordable and lightweight. Their monthly service plans buy credits for non-emergency messaging, tracking, and more.
Two-Way PLBs

The Ocean Signal rescueME PLB1 is the lightest device we reviewed, at a mere 2.5 ounces. It has only one function — to summon help by sending an SOS signal on the 406 MHz Cospas-Sarsat distress network. It has no GPS, no two-way communication or other features, and it requires a free registration with the National Oceanic and Atmospheric Administration (NOAA).

Most devices that offer emergency messaging can also send out an OK message when triggered by the SOS button. This feature allows you to notify rescuers that everything is fine and they should continue their search or recovery operation, thereby expediting the process. Activating the SOS button on these devices will also cause the devices to send a digital signal with their unique UIN, allowing rescuers to hone in on the source of the distress call.

These devices, such as the SPOT X, inReach Mini 2, ZOLEO, Garmin devices and the Somewear Hotspot, also have a battery life indicator that alerts you when it’s time to change the batteries. Some also allow you to send custom messages that will appear on the screen of any rescuer who uses the device to monitor your location or check-in.

These devices rely on a satellite network, such as Iridium or Globalstar, and operate on a subscription basis, with monthly or yearly charges in addition to the device purchase price. Unlike the government-backed PLBs, these devices do not use NOAA’s public response system and instead route emergency calls through a commercial satellite network to a 24/7 command center.
Here's my website: https://mandowndevice.com/