Garmin, SPOT, Ocean Signal SOS Systems Compared
Adventure travelers rely on satellite SOS devices, but response systems from Garmin, SPOT, and Ocean Signal vary in communication style, networks, and response centers.
Pressing an SOS button on a satellite communication device triggers a complex rescue machine that varies significantly between major providers like Garmin, SPOT, and Ocean Signal, differing in communication capabilities, satellite networks, and the use of intermediary response centers.
Garmin estimates it has received over 250,000 SOS alerts since 2007 from virtually every country. More than 20,000 required responses from the company, averaging over 1,000 per year. Calls continue to increase, with the company reporting 3,000-plus yearly incidents in 2025. Trail and mountain calls had "notably" increased. The broader trend is similar. The Cospas-Sarsat satellite system, used by Ocean Signal, recorded well over 1,000 search-and-rescue events in 2024, up from a few hundred per year in the 1990s. Beacons are now standard field gear, with Cospas-Sarsat estimating over 3.35 million devices capable of communicating with its network were deployed in 2024. In 2024 alone, the parent company of Garmin competitor SPOT reported a gigantic 35% year-over-year increase in device sales.
Garmin's Iridium-Based System
Garmin's SOS process uses the Iridium satellite network and is communication-forward. When triggered, the device sends GPS coordinates to the Garmin Response Center, a 24/7 emergency coordination hub. The center acknowledges the alert and opens two-way text communication to assess the situation. Coordinators simultaneously work to contact a local rescue agency.
The user's location updates automatically every minute for the first ten minutes of an SOS event, then once every ten minutes thereafter. Garmin coordinators also reach out to the user's emergency contacts if available and relay information between rescuers and the user. The company continues monitoring the user's location until the incident is resolved.
SPOT's Globalstar Network Process
SPOT devices utilize the Globalstar satellite network and route alerts through a third-party response center, FocusPoint International. The process mirrors Garmin's on newer devices. When an SOS is triggered, coordinates are sent to FocusPoint's 24/7 center, which confirms the location and contacts a local search-and-rescue agency.
Coordinators may contact the user and their emergency contacts to gather information, following the user's pre-set instructions. Communication capabilities vary by device. The SPOT X model provides two-way text messaging with rescue coordinators and sends location updates every 2.5 minutes until an alert is acknowledged, then every 5 minutes. Older SPOT Gen4 and earlier devices are limited to one-way communication.
Ocean Signal's Direct Satellite Alert
Ocean Signal's rescueME PLB3 beacon operates differently, bypassing commercial response centers entirely. It links directly to the Cospas-Sarsat international search-and-rescue satellite system, which requires no subscription. When activated, the beacon transmits its unique identity and GNSS location at 406 MHz to Cospas-Sarsat satellites.
The alert is routed through a ground station to a Mission Control Center and then to a Rescue Coordination Center. The RCC uses the beacon's registration information, such as typical usage and an emergency contact for the specific trip, to verify the emergency before dispatching local resources. Communication is extremely limited, with no text or voice messaging available to the user.
Where Ocean Signal stands out is in locating the user. In addition to the global alert, the PLB3 continuously transmits a 121.5 MHz radio homing signal that rescuers can follow once nearby. The company reported that, at sea, it also broadcasts an AIS distress position to nearby vessels equipped with Automatic Identification Systems.
