Two-way satellite communicators – which is best?

In this article, we look at the key features and differences between the two-way satellite communicators and which is best.


With two-way satellite communicators, there are several things to think about.

These are -

- The two-way satellite device itself

- What are you going to use it for

- Reliability of the signal, as two-way satellite communicators work in different ways

Taking onboard the above points, the thought process you need to work through –

1. The two-way satellite communication device – the options

For this article, we are going to look at and compare not only the devices but also the related contract fees for the following satellite communicators -

- Spot Gen 4

- Garmin inReach Messenger

- Garmin inReach Messenger Plus

- Garmin inReach mini 2

- Zoleo

- Garmin GPSMAP67i

- Garmin Montana 710i

- Garmin Montana 760i


2. What are you going to use it for?

The 6 features you get with a two-way satellite communicator are -

- The experience/ reassurance you receive when you press the SOS button

- Live tracking

- Sending pre-set messages

- Sending messages composed by user

- Receiving messages

- Navigational experience

Not all two-way satellite communicators do all of the above; also, the contract you sign up to with the provider will make some features more expensive to use.

The key features you want to use the two-way satellite communicator for will make the largest reasons you buy one product over another.

3. The experience/ reassurance you receive when you press the SOS button

What happens when you press the SOS button?

When you press the SOS button on a two-way satellite communicator, such as a Garmin inReach, SPOT, or Zoleo, the following sequence typically occurs:

-       Immediate Distress Signal Sent

• The device sends an emergency signal via satellite to a global emergency response coordination centre.
  
  
• Devices like the Garmin inReach use the Garmin Response Centre, while SPOT devices use Globalstar’s emergency services and Zoleo uses Global Recue.
  
  
• The distress signal contains your exact GPS coordinates, time, and often a message stating that you have triggered an SOS.

-       Confirmation & Communication

• On a two-way communicator, the response centre can send a message back to you asking for details of the emergency.
  
  As the Spot Gen4 cannot receive messages, you will not get this feature, so there is always that doubt in your mind, has anybody received it?
  
  
• If you are able to reply, you can provide critical information such as the type of emergency, injuries, and required assistance.
  
  
• If you cannot respond, emergency services will assume the worst and begin coordinating a rescue.

-       Emergency Services Notified

• The response centre assesses the situation and contacts the local emergency services best suited to your location.
  
  
• For example, if you're in the UK, this could be Mountain Rescue, Coastguard, or the Police.
  
  
• They will provide rescuers with your GPS location, personal details (if registered), and any information received from your messages.

-       Continuous Tracking & Updates

• Your device continues to transmit your live location at set intervals so rescuers can track you.
  
  
• If you move, they can adjust their route accordingly.
  
  
• Some devices allow you to cancel the SOS if the situation improves.

-       Rescue Coordination

• Depending on your location, rescue times can vary.
  
  
• In remote areas, a helicopter, boat, or ground team may be deployed.
  
  
• If you're in a foreign country, the response centre may contact your embassy or insurance provider, so it is important to put your insurance details into the relevant admin section for the of two-way satellite communicator software, before you head overseas.

Key Considerations

• Battery Life: Keep your device charged, as a weak battery could affect SOS reliability.
  
  
• Clear View of Sky: Ensure your device has a direct line to satellites for the best signal strength.
  
  
• False Alarms: Some devices require a long press or a protective cover to prevent accidental activation.
  
  
• In a previous article, we looked at what happens when you press an SOS button.

 

4. Live Tracking

Two-way satellite communicators offer live tracking, allowing others to follow your journey in real time. This feature is particularly useful for hikers, ultra runners, mountaineers, and remote workers who need safety monitoring or want to share their progress with friends, family, or support teams. 

Here's what to expect from live tracking on different satellite communication devices.

-       How does live tracking work?

• The device sends regular location updates via satellite, usually at intervals ranging from 2 minutes to an hour (depending on settings and subscription level).
  
  
• Your real-time location is visible on an online map, accessible via a private link or a tracking portal.
  
  
• If the device supports messaging, you can send waypoints or check-in messages alongside location data.

- Key Features of Live Tracking

a) Customisable Tracking Intervals

• Devices allow users to adjust tracking frequency based on battery life, data plan, and movement speed.
  
  
• Faster tracking (e.g., every 2 minutes) is ideal for ultra runners, expeditions, or guided trips.
  
  
• Longer intervals (e.g., every 30–60 minutes) conserve battery for multi-day treks or ocean crossings.

b) Public & Private Sharing

• Some devices let users create password-protected tracking pages to share location privately.
  
  
• Others (like Garmin Explore) offer public tracking pages for races or expeditions.

c) Emergency Notifications

• Some devices integrate automated alerts if the user stops moving for an extended period (e.g., in a fall or medical emergency).
  
  

-       Live Tracking on Popular Two-Way Satellite Communicators

Device	Tracking Method	Update Frequency	Unique Features
Garmin inReach	Garmin Explore Map Share	2-30 min	Two-way messaging & SOS with GEOS
Spot	Spot Shared Page	2.5 - 60 min	Customisable movement alerts
Zoleo	Zoleo Tracking Map	6 min – 60 min	Location sharing via SMS & email

 

-       User Experience: What Live Tracking Feels Like

• For the user: You’ll see a status indicator confirming each location update is sent successfully. You might also receive acknowledgements from followers or support teams.
  
  
• For the viewer: Friends and family can see your position on a live map, along with altitude, speed, and direction.
  
  
• For rescue teams: Some devices allow live location sharing directly with emergency responders in an SOS scenario.

 

-       The best contracts for those wanting to utilise live tracking

• Live tracking can often be the largest cost when thinking about which device/ contract will suit you best
  
  

- Some current cost examples, using a product 12 months a year, when using live tracking

- Spot Gen 4 -

£176.21 year 1, then £151.07 ongoing yearly cost – you get this included in the standard Spot Tarif.

- Garmin inReach devices -

£399.87 year 1 (£219.39 with no live tracking)
then £359.88 ongoing yearly cost (£179.40 with no live tracking)

- Zoleo -

£293.00 year 1 (£239.00 with no live tracking)
then £270.00 ongoing yearly cost (£216.00 with no live tracking)

Below is the live tracking on a recent walk with the Spot Gen 4

5. Sending pre-set messages

Pre-set messages on two-way satellite communicators allow users to send quick, predefined messages to contacts without having to type a new one each time.

messages are particularly useful for saving battery life, ensuring quick communication in remote areas, and avoiding excessive data charges, as unlimited pre-set messages are included in all contracts currently on the market.

-       What Are Pre-Set Messages?

• Pre-written messages that you create in advance and can send with one press.
  
  
• Used for quick check-ins, status updates, or non-emergency notifications.
  
  
• Do not count towards messaging limits on all satellite plans.
  
  

-       Common Examples of Pre-Set Messages

Most devices allow users to customise three or more pre-set messages. Examples include:

✅ “I’m OK. No need to reply.” (For regular check-ins.)
✅ “Arrived at my destination safely.” (Useful at waypoints or camp.)
✅ “Delayed but all good.” (For minor setbacks like slow progress.)
✅ “Heading back now.” (For signalling a change of plan.)
✅ “Need non-emergency assistance.” (Useful for minor gear failures or navigation issues.)

Some devices allow location attachment, meaning your recipient can click on the message to see your exact coordinates.

-       You can change pre-set messages on

Spot Gen4 satellite communicators

-       You cannot change pre-set messages on

Garmin inReach satellite communicators

Zoleo two-way satellite communicators

 

6. Sending messages composed by user

Unlike pre-set messages, user-composed messages allow you to type and send custom texts via satellite, just like a normal SMS or email—but without needing a mobile network. These messages are a key advantage of two-way satellite communicators over one-way devices, as they enable real-time conversations in remote areas.

You only have the ability to send/ receive user-composed messages from Garmin inReach devices and Zoleo products.

Often the limitation can be the lack of a full QWERTY keyboard, but you will find this on a Montana 710i/ 760i or any other Garmin inReach product or Zoleo, when tethered with a mobile phone, that can be used as a keypad in the relevant app for each of these products

-       How User-Composed Messaging Works

• You can type a custom message on the device itself (if it has a keyboard) or via a paired smartphone app.
  
  
• The message is sent via satellite network (e.g., Iridium for Garmin inReach and Zoleo).
  
  
• It’s delivered as SMS, email, or to another satellite device, please be aware when using a Garmin two-way satellite communicator any recipient wishing to reply to a text message must download the app, whilst with a Zoleo, as it comes from a fixed mobile number the recipient can just reply to the text message.
  
  
• The recipient can reply, creating a full two-way conversation.
  
  
• Messages often include GPS coordinates, allowing the recipient to track your location, this can be selected as an option by the person sending the message from the two-way satellite message.
  
  

7.     Receiving Messages on a Two-Way Satellite Communicator

One of the biggest advantages of two-way satellite communicators over one-way devices is the ability to receive messages in addition to sending them.

Devices that receive messages -

Garmin inReach products
Zoleo two-way satellite communicator

This means you can stay in touch, get real-time updates, and even respond to emergency services if needed. Here’s how it works.

-       How Receiving Messages Works

• Messages sent to your device are received via satellite network (e.g. Iridium)
  
  
• Your device downloads new messages automatically when it connects to a satellite.
  
  
• If you’re in an area with poor satellite visibility (e.g., deep valleys, dense forests), messages may be delayed until you have a clearer sky view.
  
  
• Some devices allow you to request new messages manually, forcing a satellite check.

- Who Can Send Messages to You?

• Friends & Family: They can send messages via SMS (for Zoleo), email, or dedicated web portals (like Garmin’s MapShare).
  
  
• Rescue Services: If you trigger an SOS, the response centre can send and receive messages to assess the situation.
  
  
• Weather Services: Some devices let you request weather forecasts, which are sent back as a received message.
  
  
• Expedition Support Crews: Teams monitoring your journey can send instructions, route changes, or alerts.

 

8.     Navigational experience from a two-way satellite communicator

Two-way satellite communicators are primarily designed for messaging and emergency communication, but the inReach Mini 2 also offer basic to advanced navigation features.

The Garmin GPSMAP67i, Montana 710i and 760i are really dedicated GPS navigation devices, with the addition of Two-way satellite communication.

Zoleo and Spot Gen4 – no navigational experience, pure communication

Garmin inReach mini 2 - Breadcrumb track, waypoints, compass, will navigate a ‘course’, no mappind on device but can be paired with explore app to get basic maps for UK.

In the video below, you will see the navigational experience of the Garmin inRaech mini 2

Garmin GPSMAP67i, Montana 710i and 760i – these are primarily navigational devices, with the ability to display Ordnance survey maps for the UK on the screen, but they also have the off-grip two-way satellite communication ability on these top-end products.

Summary

We very much hope this has given you a better understanding of the subject of two-way satellite communication when off-grid.

Please find below the ‘walk and talk’ videos and other videos you may find useful.

If you do have any questions, please do get in touch with the team here at GPS Training

Walk and talk - Garmin inReach messenger

Walk and talk - Zoleo