Even with VSAT or STARLINK internet on board, a satellite phone still earns its own place on the bridge. When the internet link drops or the onboard network fails, it gives you a separate line to call the shore regardless of the link. Here is what to know when choosing a satellite phone for ships: how the Inmarsat satellite phone service works, fixed versus handheld phones, and how to install and run them.
1. Why ships still need a satellite phone
- An independent line: a satellite phone does not go through the vessel's internet link, firewall or onboard network, so you can still call during a main-link outage, a network equipment fault, or when the onboard network has been isolated after a cyber incident.
- The last means of contact in your procedures: when the incident response procedure states who to call, and on which number, if the internet goes down, the satellite phone number is the reference. See what a cyber security manual for ships and its incident response procedure must include.
- Not GMDSS: a satellite phone does not replace statutory GMDSS distress and safety equipment. Distress communication follows GMDSS equipment and procedures; the satellite phone is for business and emergency contact with the shore office and others.
2. How the Inmarsat satellite phone service (GSPS) works
- Geostationary satellites: the phone talks to satellites fixed above the equator, so the phone or its antenna needs a clear view of the sky in that direction — generally towards the south in the northern hemisphere.
- Coverage: usable across most sea areas except the polar regions. If you trade on high-latitude routes near the poles, check coverage in advance and consider a low-earth-orbit service that reaches the poles as well.
- One number: Inmarsat satellite phone numbers start with +870, and the same number makes and receives calls in any sea area where the satellite is in view. Register it in the shore office's emergency contact list.
- SIM and airtime: the phone needs an Inmarsat SIM and an activated airtime plan (prepaid or postpaid). With prepaid, track both the validity period and the remaining airtime.
- Beyond voice: voice is the core service; depending on the device, SMS, e-mail and position reporting are also available. Decide which functions you need before choosing the device.
3. Fixed or handheld?
- Fixed (installed on board): an external antenna goes on deck and the handset is mounted on the bridge. You can call from inside, and because it stays powered from the ship's supply, incoming calls are not missed. It suits the everyday line used by the watchkeeper. Example: Inmarsat satellite phone SPST-1100A.
- Handheld: carried anywhere — on deck, in a lifeboat or off the vessel. Inside the hull it struggles to find the satellite, so calls are made outdoors with the antenna extended and a clear view of the sky, and the battery needs looking after. Example: IsatPhone 2 handheld satellite phone.
- Both together: split the roles, with the fixed phone for routine and emergency contact from the bridge and the handheld kept in the grab bag for situations outside the vessel such as abandoning ship.
- What to weigh: who uses it and where (always on the bridge or carried for emergencies), the functions you need (SMS, e-mail, position reporting), coverage on your routes, and installation space alongside existing satellite equipment.
4. Installing a fixed satellite phone
- Antenna position: choose a spot where the sky towards the satellite is not blocked by the mast, funnel or other antennas. Avoid the height swept by the radar beam and the area right next to other satellite antennas.
- Cabling: the longer the cable between antenna and handset, the weaker the signal, so keep the route short and waterproof deck penetrations and connectors.
- Power: connect to the ship's supply, ideally behind a UPS or other emergency power so it still works during a blackout.
- Location and instructions: mount it within easy reach of the watchkeeper and post how to dial (country codes and the +870 number format) and the emergency contact list beside it.
5. Ready for an emergency: checks and routines
- Regular test calls: make a test call to the shore office at a set interval and log the result, checking satellite reception and call quality.
- Handheld battery and storage: check the charge regularly and keep the phone in a fixed place with the grab bag; make sure every crew member knows where it is.
- SIM and airtime: manage prepaid validity and remaining airtime, or the postpaid contract status, from the shore side too, so the phone is never unusable when it is needed.
- Contacts and handover: store shore emergency contacts both in the phone and on a paper list, and hand over how to use it at crew changes.
- Add it to routine checks: include the satellite phone in the routine checks for bridge and communication equipment so it is not missed. For onboard equipment checks, see 7 preventive checks that reduce vessel IT failures.
Ocean Connect supplies fixed Inmarsat satellite phones and the handheld IsatPhone 2 with a partner. See vessel satellite communication for main and backup link design with VSAT, STARLINK and more, and if you are considering a satellite phone, contact us via the online inquiry form or our emergency 24-hour helpdesk (+82-70-7588-0611~0612).