# Iridium GMDSS Systems, Installation & Support

> Iridium GMDSS supply, installation and support: Lars Thrane and Intellian systems, Inmarsat C replacement, polar coverage and Safety Voice. Request a quote.

URL: https://satcenter.tv/iridium-gmdss/

Satellite distress alerting, direct Safety Voice with rescue authorities and reception of maritime safety information, with coverage that reaches the Arctic, Antarctica and the North Pole. Satcenter supplies, installs and commissions Iridium GMDSS systems for shipowners, vessel managers and shipyards, from Rotterdam and Istanbul.

## What is Iridium GMDSS?
**Iridium GMDSS is a maritime satellite distress and safety service that runs over the Iridium network.** It is part of the Global Maritime Distress and Safety System (GMDSS): the international framework that lets ships send distress alerts, communicate with rescue authorities and receive safety information.

The IMO recognises both **Iridium and Inmarsat** as providers of satellite communication systems for GMDSS. An approved Iridium GMDSS installation can meet the satellite communication requirements that apply within the vessel's wider radio safety arrangement.

The GMDSS terminal is one part of that arrangement. VHF/DSC, MF/HF where required, EPIRBs, search and rescue locating devices and MSI receivers are assessed for the vessel as well.

Satcenter helps you choose a system that suits your vessel, flag and trading area: from a dedicated safety terminal to an Iridium Certus GMDSS system that also carries operational voice and data.

## What happens when you activate a distress alert?
An Iridium GMDSS system brings three essential satellite safety services together. Satellite coverage and MSI broadcast availability are different things: the operational SafetyCast status of the NAVAREAs and METAREAs on your routes is checked together with the flag requirements.
- **Distress Alert**: A dedicated distress control sends the vessel's identity, position and distress details to a Rescue Coordination Centre (RCC), so rescue authorities can identify the vessel and start coordinating assistance.
- **Safety Voice**: The bridge team speaks directly with the rescue authorities to explain the situation. GMDSS distress and safety traffic is handled with priority over routine commercial traffic.
- **Maritime Safety Information (SafetyCast)**: Iridium SafetyCast delivers navigational warnings, meteorological warnings and forecasts, and search and rescue information from participating authorised providers.

## Why choose Iridium GMDSS?
Iridium GMDSS combines polar coverage, direct voice contact and compact retrofit options. Selected Certus systems also carry routine voice and IP data next to the safety services.
- **Coverage from ocean routes to polar waters**: The low Earth orbit network covers the planet pole to pole, including the geographic North Pole. Relevant for expedition vessels, research ships, fishing fleets and ships trading at high latitudes. Reception still depends on correct installation and a clear antenna view of the sky.
- **Direct voice contact in an emergency**: Safety Voice lets the bridge describe the incident and discuss rescue coordination with an RCC. Inmarsat C supports messaging and alerting, but no voice calls.
- **Safety and operational connectivity**: Certus GMDSS systems such as the LT-4200S or C700 GMDSS also carry routine calls and IP data, next to Starlink, OneWeb or VSAT. Distress and safety functions always keep priority.
- **A choice of retrofit options**: Different antenna sizes, bridge interfaces and data classes let the system be chosen around the vessel. In some approved configurations, suitable existing cabling can be reused after inspection.

## Iridium GMDSS vs Inmarsat C: which should you choose?
Both are established options for maritime satellite safety communication. The right choice depends on the vessel's routes, existing equipment, required functions and approved radio arrangement.

RequirementIridium GMDSSInmarsat C / approved Mini-C GMDSS**Satellite network**Low Earth orbit (LEO)Geostationary (GEO)**Coverage**Pole to pole, including polar watersExtensive ocean coverage, excluding the extreme polar regions**Satellite distress alerting**Yes, with an approved systemYes, with an approved system**Voice communication**Safety Voice and routine voice, depending on configurationNo voice through Inmarsat C**Safety information**Iridium SafetyCast; check operational broadcasts for the routeInmarsat SafetyNET**Routine communications**Voice and messaging; Certus models add IP dataLow-rate messaging and reporting**LRIT and SSAS**Available on selected approved configurationsAvailable on suitably equipped and approved configurations**Replacement decision**Subject to vessel, flag, MSI and survey assessmentCan remain appropriate for an existing compliant installation### When Iridium is a strong option

Consider Iridium GMDSS when the vessel needs polar satellite coverage, direct safety voice, a replacement for ageing equipment, or a Certus installation that combines safety services with essential IP connectivity.

### When keeping Inmarsat C makes sense

A working, supported Inmarsat C installation may continue to meet the vessel's needs. Keeping it avoids unnecessary replacement work and can support the required MSI reception arrangement. Installing Iridium alongside Inmarsat C can add complementary capabilities, but the overall arrangement is assessed as a whole: two terminals do not automatically fulfil every redundancy requirement. For Inmarsat services, see [Inmarsat maritime connectivity](https://satcenter.tv/inmarsat-maritime-connectivity/).

### Can Iridium replace Inmarsat C?

An approved Iridium installation can replace Inmarsat C in an accepted vessel configuration, but it is not an automatic equipment swap. Before replacement, the review covers:

- Flag acceptance and trading area
- MSI reception (NAVTEX, SafetyNET or SafetyCast)
- Radio redundancy and reserve power arrangements
- LRIT and SSAS functions that currently run on the old equipment

For Dutch-flagged vessels, published guidance sets specific MSI conditions and asks owners planning a replacement to contact the vessel's Recognised Organisation. Satcenter plans the technical scope and coordinates the required checks with the parties involved.

## Which Iridium GMDSS systems are available?
The product families below are a starting point for selection. Final supply is confirmed against availability, current certificates, firmware, accessories and acceptance for your vessel.

SystemService classVoiceMaximum IP dataBest suited to**Lars Thrane LT-3100S**Iridium GMDSSSafety Voice and routine voiceModem data, SMSDedicated safety installation**Lars Thrane LT-4100S**Certus 1002 channels88 / 22 kbpsGMDSS with light IP data**Lars Thrane LT-4200S**Certus 2003 channels176 / 176 kbpsGMDSS with more operational data**Intellian C100M GMDSS**Certus 100YesCertus 100 classCompact safety retrofit**Intellian C200M GMDSS**Certus 200YesCertus 200 classSafety, voice and essential IP data**Intellian C700 GMDSS**Certus 700YesCertus 700 classSafety plus higher-capacity L-band### Lars Thrane LT-3100S GMDSS: dedicated distress, safety voice and messaging

The LT-3100S combines Distress Alert, Safety Voice and MSI reception with routine voice, SMS and modem data. It also supports SSAS and LRIT in the appropriate configuration. A practical choice for vessels that want a dedicated Iridium safety installation without Certus IP bandwidth.

### Lars Thrane LT-4100S GMDSS (Certus 100): GMDSS with light IP connectivity

The LT-4100S adds Certus 100 connectivity with two voice channels and maximum IP data rates of 88 kbps download and 22 kbps upload. It suits vessels that need essential messaging, light data applications and fixed satellite telephony alongside the safety functions.

### Lars Thrane LT-4200S GMDSS (Certus 200): more operational data capacity

The LT-4200S supports three voice channels and IP data rates of up to 176 kbps in both directions. It is an option for operational email, selected remote applications and controlled backup connectivity.

### Intellian C100M GMDSS (Certus 100): compact safety installation and retrofit flexibility

Intellian announced the commercial launch of the C100M GMDSS in July 2026 with MED Wheelmark and UK MER Red Ensign approvals. The system pairs a compact antenna with a bridge-mounted Safety Control Unit. Support for both standard coaxial and NMEA 2000 cabling can allow suitable existing antenna cabling to be reused after inspection.

### Intellian C200M GMDSS (Certus 200): integrated safety, voice and essential IP data

The C200M GMDSS combines the maritime antenna, the below-deck unit and a dedicated Safety Display Terminal, bringing GMDSS functionality together with Certus 200 connectivity for routine operational applications.

### Intellian C700 GMDSS (Certus 700): safety services and higher-capacity Certus

The [Intellian](https://satcenter.tv/intellian-maritime-connectivity-solutions/) C700 GMDSS combines Iridium safety services with Certus 700 operational connectivity: an option for vessels that want GMDSS and an L-band companion to a higher-capacity broadband system. Existing C700 installations may have an upgrade path with a Safety Display Terminal and handset. Compatibility, software, accessories and flag acceptance are confirmed for each installation.

### Thales WaveLINK GMDSS: integrated bridge safety interface with VesseLINK

Thales describes WaveLINK as a GMDSS solution that combines a dedicated panel computer with VesseLINK on Iridium Certus GMDSS. Its published functions include distress alerting, Safety Voice, MSI, LRIT and SSAS. We check the current approved configuration, equipment compatibility and delivery status for your project.

### Furuno SOLION-100 (announced): for upcoming retrofit and newbuild projects

Furuno unveiled the SOLION-100 in September 2026, with retrofit availability expected in late 2026 and newbuild availability in 2027. For projects considering this terminal, Satcenter reviews the published specification and confirms availability and approval status before quotation.

## Replacing Inmarsat C or upgrading a C700?
Send us your existing terminal model, vessel flag and trading area. We will recommend a suitable Iridium GMDSS system and outline the installation scope.

## Does a standard Iridium phone or Certus terminal count as GMDSS?
**No.** An Iridium 9555 or Extreme 9575 handheld satellite phone does not replace an approved GMDSS terminal.

Likewise, a standard Intellian C700, C200M, SAILOR 4300 or Thales VesseLINK installation should not be assumed to be GMDSS compliant. Compliance depends on the complete approved equipment configuration, including the safety interfaces, software, power arrangements and installation.

For routine satellite voice and data, and for Iridium as the third link in a failover setup, see our page on [Iridium Certus maritime connectivity and satellite phones](https://satcenter.tv/iridium-certus-maritime-connectivity/).

## Iridium GMDSS installation and commissioning by Satcenter
We plan the equipment and the installation together, so the system fits the vessel's bridge, antenna arrangement and operational schedule. Our project scope can include:

- Review of vessel details, flag, routes and existing radio equipment
- System selection and review of current equipment approvals
- Antenna positioning, mounts and cable-route planning
- Installation of the terminal, safety display, handset and alarm accessories
- Power and reserve-power integration suited to the approved arrangement
- Vessel identity configuration and service activation
- GNSS, alarm and bridge interface integration where applicable
- Coordination of LRIT or SSAS migration when included
- Approved test procedures, functional checks and commissioning records
- Crew familiarisation and installation documentation
- Coordination with the owner, shipyard, service provider and survey parties

Formal statutory acceptance and certification remain with the relevant authorised parties. Tests follow the prescribed test procedures.

**Planning a port call or dry dock?** Share the port, attendance window and existing equipment list, and we will prepare the installation scope.

## Iridium GMDSS installation in Rotterdam, Europe and Türkiye
Satcenter works from Rotterdam and Istanbul. We coordinate equipment delivery, engineer attendance and commissioning around the vessel's schedule, and arrange international mobilisation according to the project scope and engineer availability.
- **Netherlands and the ARA region**: Installations and retrofits in Rotterdam, Amsterdam and Antwerp, during port calls or at the shipyard.
- **Türkiye**: Attendance from Istanbul for vessels in Turkish ports and shipyards, including dry-dock projects.
- **Other ports by arrangement**: Engineers mobilised to other European and international ports, with equipment shipped ahead to the vessel.

## Ongoing support and system management
Satcenter supports your installation after handover with troubleshooting, configuration help and planned service attendance. Depending on the agreed scope, support can include:

- Remote diagnostics through the terminal's web interface
- Approved software maintenance
- Coordination with the airtime service provider
- Fault investigation and onboard attendance
- Preparation for equipment changes and surveys

For Certus GMDSS systems that also carry operational data, we manage traffic policies, application access and backup connectivity settings, with safety traffic always taking priority. Round-the-clock help is available through our [24/7 maritime support](https://satcenter.tv/24-7-maritime-support/).

## Iridium GMDSS price: what does a complete system cost?
The installed price depends on the terminal, required accessories, cabling, power arrangements, airtime service and commissioning scope. A useful quotation identifies:

- The terminal and approved safety equipment
- Displays, handsets, alarm panels and required accessories
- Mounting, cabling and installation labour
- Activation and recurring service charges
- Commissioning, documentation and any external survey costs
- Optional LRIT, SSAS and operational data services

Send us your vessel information and we will prepare an itemised proposal covering equipment, installation and ongoing service.

## Iridium GMDSS: frequently asked questions
### Is Iridium GMDSS recognised by the IMO?

Yes. The IMO recognises Iridium as a satellite communication system provider for GMDSS. The selected equipment and the complete installation must also meet the requirements that apply to your vessel.

### Is Iridium GMDSS mandatory?

GMDSS requirements generally apply to SOLAS passenger ships and to cargo ships of 300 GT and above on international voyages, subject to applicable provisions and exemptions. Iridium itself is not mandatory: the required radio arrangement depends on the vessel and its operation. National rules can also apply to other vessels.

### Does Iridium GMDSS work at the North Pole?

The Iridium satellite network covers the North Pole and the other polar regions. Installation suitability, environmental limits and the required MSI reception arrangement are assessed as well.

### Does global coverage mean SafetyCast is operational everywhere?

No. Network coverage and operational NAVAREA/METAREA broadcasts are separate matters. The broadcast status and flag requirements are checked for the planned routes.

### What about Sea Areas A3 and A4?

Under the modernised SOLAS definition, Sea Area A3 depends on the recognised satellite service supported by the ship earth station on board. Iridium's global footprint can extend the vessel's A3 coverage into polar waters. This does not remove the need to assess the full radio equipment arrangement.

### Can Iridium replace our Inmarsat C terminal?

In an accepted vessel configuration, yes. Before replacement we review flag acceptance, trading area, MSI reception, radio redundancy, power arrangements and any LRIT or SSAS functions that run on the existing terminal.

### Can I use the same system for GMDSS and backup internet?

Selected approved Certus GMDSS systems support routine IP data as well as safety services. Available bandwidth and permitted use depend on the terminal, configuration and service plan, and safety traffic always takes priority.

### Can Starlink replace GMDSS?

No. A standard Starlink installation is not an approved GMDSS ship earth station. It supports everyday connectivity, while dedicated approved equipment provides the required safety communication functions. See our [Starlink maritime installation](https://satcenter.tv/starlink-maritime-installation/) page.

### Does Satcenter provide installation and support?

Yes. Satcenter provides equipment supply, installation, commissioning and ongoing technical support, with attendance and service scope agreed around your vessel.

## Contact

Email: info@satcenter.tv · Phone: +31 85 560 71 20 · https://satcenter.tv/contact