The journey itself is often the riskiest part of a trip for your phone bill. On ships, and on aircraft with mobile service, phones can join onboard satellite-linked networks billed outside normal roaming bundles, often at high rates. Keep mobile data off at sea and in the air, and buy onboard Wi-Fi only if you need it.
Why are onboard networks billed differently?
A cruise ship or an aircraft that offers mobile service carries its own small mobile network on board. That network connects to the rest of the world through a satellite link, which is expensive to run. To your phone it looks like just another network to roam on, but to your carrier it is a special partner with special prices.
Three things follow from that:
- Normal roaming bundles may not apply. A daily pass or an included-roaming allowance usually covers land networks in listed countries, not onboard satellite networks.
- Regional rules may not apply. The European Commission explains that EU roaming rules apply only to land (terrestrial) networks: services through satellite systems on ships or planes are not covered by the "roam like at home" price caps and are usually expensive. Close to the coast, or on rivers and lakes, a phone connected directly to a land network still roams like at home.
- Travel eSIM plans cover land networks. A country or regional eSIM is built around the mobile operators of the listed countries. It does not normally include a ship's or aircraft's onboard network.
How do you keep a cruise from costing a fortune?
On a cruise your phone's situation changes several times a day:
| Where you are | What the phone may connect to | Cheapest usual option |
|---|---|---|
| In port or near the coast | The country's land networks | Your travel eSIM or roaming pass, if that country is covered |
| At sea | The ship's onboard network | Airplane mode plus ship Wi-Fi, or no data |
| Moving between the two | Either, without warning | Manual network selection, or airplane mode until you check |
- Before boarding, turn off data roaming on your home line, as in our pre-flight settings routine.
- When the ship leaves port, switch on airplane mode and turn Wi-Fi back on if you have bought a Wi-Fi package.
- In port, switch airplane mode off and check that the phone has joined a land network in that country before you use data.
- If you see an unfamiliar network name such as one mentioning a ship, the sea or "maritime", go back to airplane mode.
- Ship Wi-Fi package for the week (example)$90.00
- Port days on a regional eSIM (example plan)$24.00
- Planned total$114.00
- Versus: one afternoon on the onboard mobile network
- 300 MB at $10 per MB (hypothetical rate)$3,000.00
The point of the example is the gap, not the figures: a planned set-up has a known total, while the onboard network has no natural ceiling unless your carrier applies a cap. If you are an EU customer, the Commission says your operator must tell you when your phone connects to such a network and stop services automatically at €50 of additional charges, or another limit you set, unless you choose otherwise; our guide to roaming caps and alerts explains the layers.
What about flights?
Most of the time, the rule is simple: airplane mode during the flight, as the crew instructs. Where a flight offers connectivity, there are two different services:
- In-flight Wi-Fi. Sold by the airline or its provider, usually by the hour or the flight, and paid by card. It does not normally appear on your phone bill. You use it with airplane mode on and Wi-Fi switched back on.
- Onboard mobile service. On some aircraft your phone can connect to an onboard mobile network for texts and data. Your carrier bills it, often at special rates outside your roaming bundle. If you do not want it, keep airplane mode on.
Is in-flight Wi-Fi worth buying? Only if the flight time has a value you can name: work you must send, a connection you must rebook. For messaging alone, many travellers wait until landing, when a pre-installed travel eSIM connects on the ground.
How do you cover layovers without a surprise?
A layover in a third country is where many travellers switch airplane mode off and start roaming without thinking. Decide in advance:
- Is the transit country on your plan? A regional eSIM may cover it; a single-country plan for your destination will not. If it is covered, check whether connecting there starts the plan's validity clock; our guide to when eSIM validity starts explains why this matters.
- Is airport Wi-Fi enough? For a short connection it often is.
- Is a separate plan worth it? For long layovers, see our cost test for a six-hour layover.
Whatever you choose, keep data roaming off on your home line while you are in transit.
Do ferries and border areas have the same problem?
Coastal ferries and border areas are usually covered by land networks, but your phone can pick up a network from the neighbouring country, which is a different country on your bill. If your plan or roaming allowance covers both countries, it does not matter. If it covers only one, select your network manually in the phone's mobile network settings, or watch which network the phone shows before you use data.
- Home line data roaming off
Before the ship or plane leaves.
- Airplane mode plan
You know when you will switch it on and off.
- Onboard Wi-Fi price checked
And bought only if the connection is worth that price.
- Covered countries known
For ports, layovers and arrival on your eSIM or pass.
- Carrier's onboard network rates known
Or onboard mobile service avoided completely.
Frequently asked questions
Does a travel eSIM work on a cruise ship?
A travel eSIM covers the land mobile networks of the countries on its list. When the ship is in port or close to the coast of a covered country, the phone may connect to a land network and the plan can work. At sea, the ship's own onboard network is not normally part of a country or regional plan.
Can I use my phone in airplane mode with Wi-Fi on?
Yes. Airplane mode switches off the mobile radio, and on most phones you can turn Wi-Fi and Bluetooth back on while it stays on. That lets you use onboard Wi-Fi without connecting to any mobile network. Follow the crew's instructions on board.
Is in-flight Wi-Fi charged to my phone bill?
Usually not. In-flight Wi-Fi is normally bought from the airline or its Wi-Fi provider and paid by card, unless your carrier or airline loyalty plan includes it. Onboard mobile service, where an aircraft offers it, is different: your carrier bills it, often at special roaming rates.
What should I do if my phone shows a ship or 'at sea' network?
Switch on airplane mode or turn off mobile data and data roaming at once, then turn Wi-Fi back on if you want to use the ship's Wi-Fi. You can also select a network manually in your phone's mobile network settings so it does not join the onboard one automatically.
Sources and notes
Prices in this article are invented examples for the arithmetic, not offers. TripoSIM facts are quoted from its public pages on the date shown and can change; the TripoSIM checkout and policy pages are authoritative. See how we compare and our editorial policy.