Can You Use A Satellite Phone In The Ocean?

You can use a satellite phone in the ocean. In fact, with a few exceptions, most sat phones can be used worldwide.

Arial correctly set for a mid-Atlantic chat 📡

The only factors which negatively affect the use of a satellite phone on the ocean are any geographical or artificial features, political influences, and system issues relating to the placement of the satellite constellations.

In the open ocean, satellite phones may be a sailor’s only marine communication connection with the rest of the world.

If there is a need for help, these systems are often the last resort to establish contact with rescue services. Therefore, choosing the appropriate system is essential to ensure that coverage is available when it is needed the most.

In this article, I provide a basic description of the technology. I also look at the services offered to sailors and which is the most appropriate provider for the different geographical regions.

I also explain what factors affect the operation of satellite phones.

🌊 Can Satellite Phones Be Used In The Ocean?

A satellite phone does not need to be in the range of cell phone towers and instead connects through orbiting satellites.

Because of this, it can receive a signal in almost any location in the world. As a result, it is handy for sailors wanting to stay in contact or summon emergency services when needed.

The variables affecting the locations of the sat phone signals include the following.

  • The number of satellites in the providers’ network.
  • The orbital location of the satellites.
  • The position of the satellite phone.
  • The phone not being in the line of sight with the satellite. (even cloud cover over the ocean can affect the ability to make a connection.)

🛰️ What Is A Satellite Phone?

A satellite phone looks like a conventional mobile (cell) phone. However, it connects to orbiting satellites instead of connecting to cellphone towers.

The sequence of a satellite phone is as follows.

  • The sat phone connects to an in-range satellite.
  • The satellites direct the signal to the network’s ground stations.
  • The ground station routes the call across conventional Telecom networks.
  • The call is connected to the receiving mobile (or satellite) device through its mobile operator’s network. 

📡 Which Satellite Phone Network Is Best In The Ocean?

Most satellite phone models can only be as good as the satellite communications network they can interact with.

The three main satellite communications networks are 

  • Inmarsat satellite network
  • Iridium satellite network
  • Globalstar satellite network

Inmarsat Satellite Network

The Inmarsat network consists of 14 geosynchronous satellites positioned above the equator. This location covers the whole earth, excluding the North and South poles.

Service has a reputation for being extremely reliable, and coverage remains even and effective. The Inmarsat satellite phone devices have the following functionality.

  • Voice calls
  • Texting.
  • Sending SOS to call for help and provide a location for rescuers.
  • Email messaging.

Iridium Satellite Network

The Iridium network has the most extensive coverage. They have a constellation of 66 satellites.

The global coverage includes Antarctica, Greenland, Alaska, and northern Canada. At low latitudes and the signals are subject to ionospheric interference.

Globalstar Satellite Network

The Globalstar satellite network is a joint venture between Loral Corporation and Qualcomm Inc. The network consists of 32 Low Earth Orbiting (LEO) satellites.

The Globalstar network is technically superior. In addition, it offers several benefits, providing a better transmission path than the other networks.

  • Path elevation angles
  • Satellite visibility
  • Susceptibility to ionospheric effects.
  • Higher downlink frequency
  • Multiple path availability.

These factors result in the Globalstar network suffering lower fade levels than Iridium and Inmarsat. Any suitably equipped cell phone can access the Globalstar constellation.

Currently, this is restricted to the Apple iPhone 14 connected to American networks, which is being operated on a trial basis.

It is reasonable to presume that the number and range of devices with this ability will grow. Dial-up coverage is available across the world except in the following countries.

  • Central and Southern Africa.
  • China.
  • Most of Asia.
  • Antarctica.
  • Greenland.
  • Alaska.
  • Northern Canada.

Direct Internet calls (Dialing #777 send) can be made from all regions except the following (and their coastal waters)

  • China
  • Belize
  • Costa Rica
  • El Salvador
  • Guatemala
  • Honduras
  • Nicaragua
  • Panama

🚦 What Affects The Use, Or Quality Of Satellite Phone Signals?

The factors which affect the quality of voice and data calls are listed below.

1️⃣ The Surrounding Terrain Next To Coastal Waters Or In Harbor

The terrain type affects the quality of the call. There must be an uninterrupted line of sight to the satellite network. There is a risk of the connection suffering quality issues or calls being dropped in the following situations.

Any calls made in harbors and coastal regions next to mountains or big city skylines may suffer from quality issues.

2️⃣ The Weather Conditions On The Ocean

If there is extensive cloud cover over the ocean, it may not be possible to establish a connection with the satellite.

3️⃣ The Equipment Being Used To Connect To The Network

The satellite telephone needs to connect with a satellite in low earth orbit. It must match the technical specifications of the service provider’s satellite constellation. Phones do not work across different satellite networks.

4️⃣ The Altitude And Orbital Locations Of The Satellites

The number of satellites and their orbit affects the quality and accessibility of calls.


Iridium has a network with 66 satellites positioned in low earth orbit. This system has the widest coverage, including at each of the poles.


The Inmarsat system has fourteen satellites in a geostationary orbit over the equator. This provides almost complete coverage of the earth, excluding the north and south poles.


Globalstar has a constellation of satellites in Low Earth Orbit. These provide coverage in the Americas, Europe, Australia, parts of Asia, and parts of Africa.

5️⃣ The Number Of Satellites In A Network

The user may experience a dropped call if the satellite cannot pass on the signal because there is no satellite within view or it is blocked.

Iridium calls are handed off to the next satellite every 50 seconds. The technology behind the handoff system is essential to whether the call is dropped or not.

The call will be dropped if one satellite in a constellation is unserviceable.

6️⃣ The Network Licensing Agreements

The satellite routes call to a base station from which the calls are routed into the conventional telecom networks.

This requires licensing agreements to be in place with different networks. In countries like China, there is resistance to some satellite phone operators, resulting in no coverage in those areas.

7️⃣ Data Congestion At The Satellites

The amount of call and data traffic causes congestion in the network. Busy Satellites may drop more calls and provide reduced call quality as they have a finite capacity.

🙋‍♂️ FAQs

Will A Satellite Phone Work In A Disaster? 

A satellite phone will generally work during a disaster. If there is cloud cover or smoke, it’ll reduce the line of sight between the satellite and the phone.

If the disaster is widespread, the call quality may reduce. This could be because the system suffers too high a call volume, causing congestion.

Will A Cell Phone Work In The Middle Of The Ocean?

A cell phone will generally not have any coverage in the middle of the ocean because there are no cell phone towers within range.

Will A Satellite Phone Work In The Middle Of The Ocean?

A Sat phone will work in the middle of the ocean as long as there is a line of site connection to the satellite. It also depends on the service provider’s constellation of satellites covering the part of the ocean where the phone is situated.

Are There Any Areas Where They Won’t Work?

Inmarsat and Globalstar do not provide coverage at the poles. In addition, Globalstar coverage is only available in certain countries, with no reception in most parts of Africa and Asia.

Are You Globally Covered, Or Do Some Only Cover A Defined Area?

Satellite phone providers provide full coverage in the areas they have satellite coverage. There must also be an agreement with the countries concerned.

💭 Final Thoughts

In a perfect world, satellite phone technology enables calls from anywhere and anytime. Unfortunately, there are restrictions to the use of the technology, and while it provides the broadest coverage, it is not complete.

Some countries, China being the most notable, do not allow sat phone coverage.

Satellite phones need a line-of-sight connection to the satellite. And the call quality may be compromised if there are any obstructions, even cloud cover.

If you are starting out on a deep-water voyage, you will need the best satellite phone for your cruising area. Carefully check which of the three provider models suits you. 

Inmarsat provides excellent quality; however, there is no coverage over the poles. Iridium provides you with a global coverage network, but the quality may not be as good. Finally, Globalstar uses the most modern technology, but full earth coverage is not yet complete.

If you are still on the fence about getting a sat phone for your boat, then consider the pros and cons of getting a satellite phone to determine whether or not it’s worth your while.

I’m the founder and chief editor here at Sailing Savvy. I spent a decade working as a professional mariner and currently, I mix those experiences with digital publishing. Welcome, and I hope that we can be the hub you need for safe passage.