Satellite Messengers

Satellite Messengers

Satellite messengers work in places that your mobile phone won't, and can be used to track your progress in real-time and update a website. Messengers can also be used to call for help.

Satellite Messengers 

Satellite Messengers

Quick Summary

Satellite messengers...

  • do not require a mobile phone signal to operate
  • communicate with commercial satellite phone Earth orbiting satellites to send messages
  • communicate with the GPS satellites to obtain an accurate position & co-ordinates
  • can send 'ok' messages by push of a button, giving reassurance to people back home if you are delayed
  • can be used to alert authorities in case of an emergency situation, when you're out of mobile phone coverage
  • can track your location as you walk, and plot such locations on Ordnance Survey maps via a web link 
  • require a monthly subscription, which is approx €8 for SPOT basic service
  • take the search out of search and rescue
  • are a massive boost to mountain & hill walking safety on

(If you'd like to hire a satellite messenger, click here)


Satellite messengers are a relatively new innovation, having been in the UK since about 2009. They are small electronic devices that work in connection with the GPS satellites and The Globalstar commercial satellite phone network. Via the GEOS Operations Center in Houston, Texas, they can send an emergency message to the UKMCC and UKARCC who will relay your position and accompanying message to the Police and Mountain Rescue Teams. These devices have more routine utilities and though they are in some ways more sophisticated, they can only derive position if they can attain a GPS lock. Transmission power is much smaller than that of their PLB equivalents, and no homing facilities exist.


There are two brands of consumer satellite messengers available in the UK: SPOT products, which is a brand of Globalstar, a satellite communication company, and inReach, which is made by DeLorme and uses the Iridium satellite network.

SPOT Messenger, Spot Connect and SPOT Gen 3 are SPOT's products aimed at hill walkers. The SPOT Connect device has the ability to send very short text messages from outside mobile phone network coverage, when the SPOT Connect is Bluetooth-linked with a Smartphone. The SPOT Messenger & Gen 3 devices can send pre-formed messages to nominated friends and family, which always include associated Lat/long positions and usually in the form of ‘OK’, ‘Help’ and Info messages. The actual text of these button-specific messages has to be composed and inserted when connected to the web, probably at home before your trip. The devices also have a tracking facility, updating the position every ten minutes via the satellites to a passworded application available through the web to user-authorised friends and family. Globalstar coverage is not worldwide, but fine in the UK. 

DeLorme inReach products benefit from global coverage as they use the Iridium satellite network, which has pole to pole coverage. These products also benefit from the ability to send and receive messages, whereas SPOT products are one way send only. Text messages of up-to 160 characters can be sent, which is approx 4 times the length of SPOT Connect's 'type & send' messages. The price of DeLorme products is coming down, but the monthly subscription is much more expensive than those of SPOT, with the cheapest subscription being $25 compared to SPOT's € 8. 

Other Satellite Communicators

Other satellite communicators exist, being:
Shout Nano – works on Iridium network - and is expensive to buy and run
Yellowbrick satellite tracker – works on Iridium network
Briartek Cerbelink – uses iridium network

Satellite Messenger Functions

Satellite messenger devices can summon help quickly where there is no terrestrial means of communication, i.e. no mobile signal, or a long walk to raise the alarm if in a group. But for the lone walker in the middle of nowhere, a satellite messenger device really could be the difference between life and death.

When the satellite messenger device is activated, a message is sent to the orbiting satellite constellation (Globalstar of Iridium), which is then relayed via the USA to the UK’s Aeronautical Rescue Co-ordination Centre (ARCC) at Kinloss Barracks in NE Scotland. It is they who contact the Police and help co-ordinate rescue resources to the location provided by the satellite messenger device.

In addition to an emergency facility, the Spot products can also send ‘ok’ and ‘help’ messages. DeLorme products have more flexibility by allowing the user to type a custom message, but also benefit from predefined message too. Both types of product allow tracking your progress on the ground by transmitting your exact location. Tracking functions may require additional subscriptions.

   SPOT Connect on rucksack strap with a clear view of the sky - providing live tracking

Live Tracking

When you use a satellite messenger to track your route, the device will send a message of your exact location to the satellite system every few minutes*, and it is this feature that is the killer application when compared to PLBs. When set up correctly, friends and family can monitor your progress on the ground via a web page, which has the following benefits:

  • your EPOC could alert the emergency services on your behalf if you did not return, and the emergency services would know your last known position
  • in the case of you walking for longer than expected, and perhaps past your ‘due back’ time, concern could be allayed if your EPOC could see that you are still moving, thus preventing a needless rescue and putting other lives at risk (you could also send an 'ok' message)
  • if you were unable to activate an emergency message, your EPOC would be able raise the alarm after an appropriate period of non-movement and past your 'return due' time - and the emergency services would know your last tracked location* 

* SPOT messenger & Connect devices 'wake up' every 10 minutes to acquire a GPS fix and transmit to Globalstar. If a fix is not available at that time, no tracking message is sent. However, the cycle continues, so another attempt will be made 10 minutes later. Therefore, 'last tracked location' location is the point from which a search would likely commence. SPOT Gen 3 can be set to track more frequently, and DeLorme inReach SE can track at intervals of between 10 minutes and 4 hours.

Below is an example of a tracked walk in a remote area of the Cairngorms, where there was no mobile signal for the duration of the day. The SPOT connect product transmitted its position every 10 minutes, thus allowing the 'folks back home' to monitor progress.

©Crown copyright and database rights Ordnance Survey licence number 100054073 2013

Each blue square is the position as transmitted from the SPOT device, via satellite, and available in near real-time to anyone to whom you’ve allowed access to your maps. (Mapping service via SocialHiking website and courtesy of Ordnance Survey – Crown Copyright.)


In remote situations for a solo walker, particularly over a multi-day trip, it has to be recommended that a Satellite Messenger is taken.  That way you can send an ‘ok’ message to your loved ones at the end of the day, or they can call for help if they don’t receive a message by a certain time - past your notification or 'return due' time. Furthermore, by using the tracking facility as above, your exact position at certain times of the day is known, and in an emergency situation where you may not be in a position to press the emergency button, your last known position would be available as an accurate place in which the rescue services could start to look. Rescuers will also know in which direction the casualty was heading and this will be very helpful. 


The SPOT products are one way messengers, and as such you do not receive a confirmation that your message has been sent. To maximise the opportunity for a message to be sent, each message is sent to the Globalstar satellite 3 times over a 20 minute period, with only one message actually being sent to your intended recipient(s). There is clear advice about how to operate the units, mainly around having a clear view of the sky and completion of message sending cycle, but you have to be aware that failure to follow the correct process will increase the chances of a message not being sent successfully.

Additional Guidance

A set of operating guidelines for SPOT products has been produced by MountainSafety, and will be available here shortly. These guidelines are around correct usage, battery life and EPOC procedures.

UK SPOT Activations
As at early 2013, SPOT product have been successfully used within the UK on two occasions.

Rescued Heart Attack Victim

In November 2010 an elderly walker was rescued by Search & Rescue helicopter when he suffered a heart attack whilst traversing the Lairig Ghru in the Cairngorms. He activated the emergency button which resulted in his timely recovery to hospital.

False Alarms

There have also been a couple of occasions where poor practice of usage has lead to rescues being mounted, but there was in fact no emergency.

The tracking facility of SPOT products has been mentioned, and if used correctly, with associated best practice, it could be a life saver. There was an incident in the Cairngorms where tracking was being used, and the track - as viewed by an EPOC back home - ran out at the top of a cliff. The EPOC alerted the police and Mountain Rescue Teams were sent to the area, only to find the SPOT users were not in any difficulty, but batteries in the SPOT device had run out, and there was no emergency at all.

A further example, where pressing the 'ok' button should have alerted the EPOC that all was ok at the end of the day. However, no such message was received. The police were called and Search & Rescue resources were despatched to a remote area of Scotland. The party was found, and they were fine. However, it was unclear whether they had failed to press the ok button as they should have done; hadn't followed correct protocol; or the message had not got through.

These latter two examples show that correct usage is essential.


An annual subscription is required to use SPOT devices, which equates to approx €10 per month.


The following news stories all relate to searches of hills & mountains for a lone walkers who'd not returned. The circumstances are known no more than the articles.