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Don't know your GSM from your PLB? Read on to learn all about communications on expedition...

We tend to go travelling or hiking to disconnect and get away from it all. Longer expeditions can give us the chance to get back in touch with nature and re-discover our sense of purpose, but in an emergency situation it is important to be able to get prompt advice and if necessary arrange an urgent medivac.

At the moment it may feel like travel and exciting trips are a long way off, but things will get better and the travel and expedition industries will bounce back- if anything I believe that travel and expedition medicine will become more, rather than less, relevant.

In the meantime, I thought it would be cool to write a series of blogs on some areas that are useful to know about when going on expedition.

To start off, lets look at the different communication options that are available to use on expeditions and the pros and cons of each of these:

Mobile Phones

It is almost impossible to go anywhere without seeing people glued to their phone screens and there is growing evidence that this is bad for us as a species! Many remote destinations now have good quality coverage with data speeds that are often better than much of the UK.


  • Handsets widely available and cheap (relatively speaking especially if you get an older handset- which will typically have a much better battery life!)

  • Coverage continues to improve year on year

  • Cost of making calls is relatively low compared with other options (e.g. Sat phone)

    • international roaming bundles have helped with this

    • can use international call plan for overseas calls

    • Can buy in-country sim cards for cheaper local calls between groups


  • Despite coverage improving, it is still not ubiquitous, particularly in the wilderness environments in which expeditions occur.

  • Mobile phones rely on line of sight communication with phone masts, so if there is a hill or forest in the way, you will not have adequate signal.

  • Similarly if the mast has a technical fault, or is mechanically damaged, it will not be possible to make a call.

  • The weather can also play a part- rain in particular is known to affect phone signal.

    • For more info on this- have a look at this excellent article here

  • Phone networks can be overloaded in emergency emergency situations and this can also prevent you from making a call- think of when you are trying to call a friend at a concert or a sports event and you cannot get through!

  • Lastly, handsets need charging and the frequency of this will vary based on use.

Satellite Phones

Satellite phones rely on a network of satellites that are either fixed above the Equator (Geostationary), or in Low Earth Orbit (LEO) (1).

There are pros and cons to both types, mainly in terms of coverage and performance, however it is worth remembering that GEO cannot cover polar regions whereas LEO can.

There are four satellite phone providers: Globalstar, Iridium, Inmarsat and Thuraya (2) some of which have a GEO network and some that use LEO satellites. For an in-depth read and to find out more about the pros and cons of the different types of coverage, and how they may affect you on expedition, have a look here.


  • Work almost anywhere in the world including the polar regions (LEO)

  • Not dependent on a local network.

  • Can be used to send data/emails/SMS (as well as make phone-calls!)

  • Can give a GPS location


  • Expensive

    • Handsets

    • Subscription fees

    • Cost per minute when making phone-calls

  • It is also expensive for an expedition company to call a sat phone from UK

  • Making a phone-call requires line of sight to the satellite- hence why handsets have large extendable external aerials. This means that making calls from under a jungle canopy or inside a vehicle, for example, may not be possible.

  • Voice quality can be poor when compared to mobile phones and there can often be a transmission delay when having a conversation

  • For emergency use you will need to have a pre-programmed landline number as it is not possible to call 999 or similar directly.

Where not to take:

If you take Sat phones to certain countries such as China, Cuba, Myanmar, Chad, Libya, you may be accused of being a spy and face arrest and possible prison.

In other countries such as India and Russia, you may be able to take a device into the country if this has been approved by the respective government departments, prior to your arrival.

For the full list- see here

If in doubt, please check with the embassy of the country in question first!

Satellite Messengers

Satellite messengers are small electronic devices that work using GPS satellites and satellite phone networks (3). Example of these include the Garmin inReach, Spot Messenger, and the Yellow Brick device.


  • Devices can be used to send and receive messages to and from phone numbers and email addresses.

  • There is the option to use either pre-written templates, user templates or write a free-text message.

  • Some models can receive long range weather forecasts and can also be used to track routes.

  • Devices often have a built in SOS/PLB function (see below for PLBs in more detail).

  • There are standalone devices available as well as newer devices that come with handheld GPS mapping software built in.

  • There are also smaller models that can be paired with a mobile phone via Bluetooth for data entry and other tasks.


  • Cost of the handset is cheaper than a sat phone but still upwards of £200

  • On top of this there is usually a subscription plan cost (up to £60 a month for unlimited messaging functionality)

  • The device needs to be able to get a GPS fix in order to communicate your location.

  • There is the possibility, cost and embarrassment of a false SOS activation occurring if the device is not packed properly in your pack!

PLB (personal locator beacon)

PLBs have been available for maritime and aviation use since the early 1980s but have only become widely used on the land more recently (4). When activated, PLBs transmit a radio signal on the 406 MHz frequency to specific satellites, which then relay the information to land-based stations (4).

In the case of the UK, this centre is the Aeronautical Resource Co-ordination Centre at RAF Kinloss in Scotland (4). PLBs also transmit a homing VHF signal that can be tracked by SAR teams that are responding to the distress signal(4).


  • One off cost (around £200-300) with no ongoing subscription costs

  • If used, many companies will replace the device for you free of charge.

  • Devices are small and easily stowed away

  • Some devices float and are waterproof

  • Devices have a 5 year standby battery life and do not require charging


  • Device must be registered with Marine Coastguard Agency in the UK or similar agency in other countries. If you forget to do this before travelling, there is no guarantee that help will be coming!

  • Details of EPOC (emergency point of contact) must be kept up to date e.g. who is in your group/where you are going etc (4)

  • It is an "All or nothing response" - there is no in between or ability to send or receive messages.

  • No way of knowing if anyone has received your distress call.

  • False activation!


I hope that this short summary has been useful. I personally have an InReach mini, that I activate the subscription for when I know I am going on an expedition without any phone signal, and also an ACR PLB as pictured above. This way I can chop and change depending on where I am going and how long I am going for.

Obviously my mobile comes as well- usually more for the camera rather than anything else. It is important to think about charging options- I would definitely recommend a high capacity power block and also a solar charger- either to recharge the phone directly or to refill the power block.

Coming up next:

Let me know if you have enjoyed this and what topics you would like to see in future posts. I am thinking of writing something to do with water sanitation next, but let me know if there is anything else that you would like to hear about!

Thanks for reading!




1. Tobias MW. How And When To Buy A Satellite Phone [Internet]. Forbes. [cited 2020 Aug 17]. Available from:

2. Mountain & Hill Walking Safety Emergency Procedures – Satellite Phone [Internet]. [cited 2020 Aug 17]. Available from:

3. Mountain & Hill Walking Safety Emergency Procedures – Satellite Messenger – Satellite Tracking - SPOT [Internet]. [cited 2020 Aug 17]. Available from:

4. Mountain & Hill Walking Safety Emergency Procedures – Personal Locator Beacon – PLB [Internet]. [cited 2020 Aug 17]. Available from:


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