Satellite messengers: What happens when I hit SOS?

Backcountry risks can be greatly mitigated with proper trip planning, but not entirely eliminated. For those “just in case” scenarios, satellite messenger like the Zoleo (my pick), Somewear Global Hotspot, and Garmin inReach Mini are worth having. Functionality includes two-way text messaging, location sharing, weather forecasts, and, most importantly, an “SOS” feature to use in case of an emergency.

The Zoleo Satellite Communicator debuted in January. It’s a 5.5-ounce two-way satellite messenger that — when paired with the Zoleo app — offers a more seamless messaging experience than other satellite messengers.

All of the aforementioned devices utilize the GEOS Worldwide system which operates the International Emergency Response Coordination Centre (IERCC) on a round-the-clock basis. GEOS provides SOS monitoring services to all countries, territories, and waters of the world covered by the Iridium satellite network with the exclusion of Afghanistan, Chechnya, Democratic Republic of Congo, Iraq, Israel (West Bank, Gaza and Occupied Territories only), Somalia, Syria, and Libya.

If you or someone you come across is in need of immediate assistance in a wilderness setting, utilizing the SOS feature on your device is the fastest and most reliable way to get help. But what is the actual chain of events that takes place once you put out the call? 

When you initiate SOS either in the device’s smartphone app or on the device itself, there is a countdown timer that allows you to cancel the call if it was made by accident. The devices also will have an audible alarm or visual indication so there is no mistaking whether or not the distress signal is being sent.

Chain of Events after SOS Activation

Action 1: You initiate the distress call via the device’s smartphone app or physical button on the device.

Action 2: The call is routed through GEOS to the IERCC via the Iridium satellite network.

Action 3: Your GPS location is shared with the IERCC and a text chain is automatically started in your smartphone app. From there, you can communicate directly with the IERCC to relay information about the situation, such as the severity of the injury and precise location (on a ridge, in a valley, etc.). If you are unable to respond via the text chain, the IERCC will initiate a rescue based on your location coordinates.

Action 4: IERCC uses its database of response agencies and contacts local emergency services that are most appropriate to the needs of the situation and location. During this time, you can continue to communicate with them via the text chain. IERCC also gets in touch with anyone listed in your emergency contacts to let them know about the issue.

Action 5: You may be put in contact with the local Search and Rescue (SAR) team if they have the capability to communicate via text message, though IERCC will stay on as well to relay information. You can also cancel your SOS call at any time if the situation changes and you are able to self-rescue.  

Action 6: Local SAR arrives and provides assistance. 

Zoleo satellite communicator. Photo by Zoleo.

The process of requesting and receiving help in an emergency situation is designed to be smooth and relatively seamless, though it isn’t necessarily fast. The amount of time it takes for SAR to reach your location and provide aid depends on the weather, your location, and what local resources are available. If requesting assistance from an extremely remote location, you should expect to wait several hours or longer for help to arrive – but with two-way communication, you will be able to stay in touch with IERCC for updates.


If you are interested in testing the SOS functionality of your satellite communication device before heading into the backcountry, you can coordinate a Test Alert directly with IERCC. It requires submitting an online request form at least 72 hours before your desired test time and you must have an active subscription with a supported device in order to do so. This is a great way to become familiar with your device and know exactly how it reacts when the SOS is activated.   

Who Pays?

No matter the severity, if a rescue takes place there is a cost to pay for the service. While having an active subscription with a satellite communication device provides the service of connecting to GEOS and IERCC, it does not cover the cost of the actual rescue. Whether or not the costs are passed on to the victim depends greatly on where it takes place and what resources were needed. It’s best to check with the agency that manages the area you will be visiting to see if there is a cost associated with rescue within their jurisdiction. You may also consider purchasing an insurance policy through the American Alpine Club or directly with GEOS which can cover a portion or all of the rescue costs depending on the selected plan.

Final Thoughts

Somewear Satellite Communicator. Photo by Somewear.

With the increased availability and lowering costs of two-way satellite communicators, it makes sense to have one on most backcountry trips. The core functionality of these devices is to provide assistance in the case of an emergency through the use of their SOS feature, but combined with two-way texting functionality they have become exceedingly useful tools. 

If you activate the SOS signal, your call will be routed through the GEOS headquarters who will dispatch local search and rescue personnel to your location while maintaining a text-based dialogue with the activator. Before heading into the backcountry, be sure to have an active subscription on your device and schedule a test with GEOS to ensure you understand how it works.  

Posted in on January 31, 2022
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  1. Hunter Hall on February 1, 2022 at 10:25 am

    I’m testing my SOS right now! #fun

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