One island, two phone rules: mobile data in Ireland, the Northern Ireland border, what an Irish SIM costs and when a travel eSIM fits

Contents:

In Ireland you can drive into the UK without a passport check and often without noticing the border at all. Your phone notices, though. North of the border it may switch to a British network, and the EU roaming rules stop there.

That border is the main thing a visitor needs to plan for. Your options are home roaming, an Irish prepaid SIM, or a travel eSIM you set up while still at home, and each one deals with the border in a different way.

This guide covers the price of each option, the coverage gaps on the west coast, and the phone settings to check before you drive north to Belfast.

👉 Ready to compare prices? See the Ireland plans.

Who pays to roam in Ireland, and who does not

Ireland had 6.4 million overseas visitors in 2025, according to the Central Statistics Office (CSO). Great Britain sent 38% of them, mainland Europe 33% and North America 24%, including 1.33 million from the United States. Each group pays a different roaming bill.

From the EU. Ireland is in the EU, and the EU’s “roam like at home” rule covers you: your home allowance works at no extra charge, within fair-use limits. Northern Ireland is a different story.

From the UK. Since Brexit, British networks are free to charge for EU roaming again, and many do. Which? (10 April 2026) found daily Europe add-ons of roughly £2 to £2.60 on the large networks; a few plans still include Europe. At £2.60 a day, a ten-day trip comes to about £26.

From the US. A day pass from a large US carrier runs about $12 per day for the first line (carrier price pages, checked 20 October 2026). One of them stops charging after ten daily fees per bill, so a long trip can still cost $120 for one phone.

From Canada. Daily international roaming on two major carriers costs CA$16–18 plus tax (checked 20 October 2026).

From the Gulf and elsewhere. Check your rate for Ireland, and separately for the UK if Belfast is on the route.

Irish prepaid SIMs: €20 for 28 days, no registration law

Irish prepaid SIMs are good value, and we will not pretend otherwise. We converted prices at the European Central Bank reference rate of 19 October 2026: €1 = $1.1225.

• Vodafone sells a tourist SIM, “Data Unlimited 5G”: €20 (about $22.45) for 28 days of unlimited data in Ireland, with 100 minutes and texts. Vodafone notes that prices at Dublin Airport may differ.
• Three charges €20 for 28 days of “all you can eat” data in Ireland on its Super Surfer prepay plan.
• Tesco Mobile, which runs on Three’s network, also lists unlimited data for €20 per 28 days.

Prices from the operators’ websites, checked 20 October 2026.

No ID law. Ireland has no national law requiring prepaid SIM registration (ComReg, the telecoms regulator, 2024). A shop may still ask for ID.

Easy to find. At Dublin Airport, Vodafone SIMs are sold at WHSmith in Terminal 1 and from vending machines in both terminals, and the airport lists a SIM sales desk in Terminal 1.

Pros of an Irish SIM:

• unlimited data for four weeks at a price no unlimited travel plan beats;
• an Irish number for B&Bs, tour operators and restaurant bookings;
• available on arrival, often without a store visit.

Cons:

• you swap out your home SIM, unless your phone takes two;
• a 28-day plan for a five-day trip;
• a queue or a vending machine after a long-haul flight.

Torrum plans for Ireland

The clock on a package starts with the first Irish connection, so buying early costs you no days.

Sized by trip: a Dublin long weekend, two weeks in Kerry and Clare, or 20 days on the whole west coast.

Billed by the megabyte, on both sides of the Irish border.

For the days you stream the match or spend hours on calls.

A week of maps, chat and photo uploads rarely needs more than 5–7 GB. Streaming and daily video calls need more.

Pay-per-MB charges $0.0011 per MB in Ireland from prepaid credit (top-ups start at $10), and money left over can be moved to a future package. Unlimited costs a set amount per period. Packages expire on their last day, whether or not the data is gone.

The Torrum Ireland profile connects through the eir and Three networks. You get data, not an Irish phone number, and the phone must be eSIM-capable and carrier-unlocked.

The honest comparison: for trips of up to 20 days, the packages cost less than a €20 Irish SIM. For a month, or if you need truly unlimited data, the Irish SIM wins.

Crossing into Northern Ireland: same island, different phone rules

The Giant’s Causeway, Belfast and Derry are all in Northern Ireland, which is part of the UK. For your phone, that changes a few things.

EU roaming rules stop at the border. ComReg says that since Brexit “roam like at home” no longer applies in the UK. EU operators may still include it, but they are not obliged to, and you may be charged for roaming in Northern Ireland. Ask your operator before heading north.

The phone can cross before you do. Along the border, a phone can pick up a stronger signal from the other side. UK rules require operators to tell customers how to avoid this “inadvertent roaming” in border areas. The usual fix is to choose your network by hand while you are near the border.

The same applies to a travel eSIM. A Torrum Ireland package works on Irish networks, and a UK package on British ones. If your phone moves to a UK network on the Donegal or Monaghan side, select eir or Three manually; our troubleshooting guide shows where that setting is.

For a day or two in the north, Pay-per-MB is the easiest answer: the same credit works on both sides, and the UK rate is the same as the Irish one. For a longer stay, add a UK package, and see our guide to mobile data in Britain.

An Irish SIM can also cover the trip: Vodafone’s PAYG Unlimited plan, for example, includes the UK in its 45 GB roaming allowance.

Paperwork, not phone signal. There are no immigration checks on the land border, but the UK Home Office says visitors who need a UK Electronic Travel Authorisation (ETA) still need one to enter Northern Ireland. That includes US, Canadian and EU citizens; British and Irish citizens do not need one. The ETA costs £20; apply online on GOV.UK before the trip north.

Autumn 2026: eir switches off 3G

Vodafone switched off 3G in October 2024, and eir is switching off 3G between 1 October and 6 November 2026, starting in Donegal (ComReg).

For most visitors this changes nothing: data runs on 4G and 5G, which ComReg says already accounted for 64% of mobile subscriptions in mid-2026.

It matters only if you travel with an old phone or a 3G-only device, such as an older tablet or hotspot. Check that it supports 4G, and see the compatible device list before you buy an eSIM.

The Wild Atlantic Way: check the map by Eircode

The west coast drive needs more planning than the cities: in mountain valleys, on headlands and on small coast roads in Kerry, Connemara and Donegal, coverage can be weaker, so check the map before you rely on it.

Ireland has a tool that helps here. Every address has an Eircode, a seven-character postcode such as A65 F4E2, and both Google Maps and Apple Maps accept it. ComReg’s outdoor coverage map lets you search by Eircode too, and shows the predicted 4G and 5G signal for each network.

Three habits for the west:

• look up the Eircode of each B&B on the ComReg map before you book, if you need to work from there;
• save the route for offline use while you are on Wi-Fi;
• save the Eircodes of your stays, so the satnav finds them even without a house number.

In an emergency, dial 112 or 999; both are free.

Islands and ferries: when the phone finds a ship network

Many trips include a boat: to the Aran Islands, to Skellig Michael, or a car ferry to Britain or France.

On the long crossings, the danger is not a lack of signal but the wrong signal. Stena Line says its ships use an onboard network run by Telenor Maritime, and that the EU price cap does not apply when your phone connects through the ship’s satellite link. ComReg gives the same warning: satellite services on boats are outside “roam like at home” and can carry high charges.

Two simple rules:

• turn on airplane mode, or disable roaming on your home line once the ferry leaves the coast;
• use the ferry’s Wi-Fi if you need to be online at sea.

A Torrum Ireland package runs only on eir and Three, so out at sea it simply has no network until you reach the coast.

On the islands, coverage varies; download what you need before the boat.

Free Wi-Fi: Dublin Airport and Irish trains

Dublin Airport handled about 36.4 million passengers in 2025. Its free network, “Dublin Airport Wi-Fi”, needs no sign-up or registration.

Irish Rail says free Wi-Fi is available on its whole fleet: look for “Irish Rail - WiFi” on Intercity trains. On the Enterprise train between Dublin and Belfast, the network is called “NI Railways WIFI”.

Train Wi-Fi runs over mobile networks, so it slows down where the signal is weak.

At home, before the airport: installing the eSIM

1. Open the device list and confirm your phone takes an eSIM and is not tied to one carrier;
2. Sign in through Google, Apple or Telegram, then buy an Ireland package, Unlimited days or Pay-per-MB credit with a card;
3. Scan the QR code while you are still on home Wi-Fi; our step-by-step install guide has screens for iPhone and Android;
4. Switch on data roaming for the Torrum line only, and leave your home line on for calls and bank codes;
5. When you land, set Torrum as the mobile data line; the package clock starts there.

Stuck at any step? Message Torrum support on Telegram.

Ireland compared: roaming, an Irish SIM or Torrum

Matching the plan to the route: Dublin, the west, the north

Three or four days in Dublin. The 7 GB Ireland package is plenty, and Dublin Airport has free Wi-Fi.

A fortnight on the Wild Atlantic Way. Take 10 GB, save offline maps for the coast roads, and Eircodes for each stay.

Up to 20 days, lots of photos and video. The 20 GB package, or Unlimited days for the heaviest days.

Dublin plus a day in Belfast or at the Causeway. Metered Pay-per-MB credit that works on both sides of the border, or an Ireland package plus a UK package for a longer northern stay. Apply for the ETA before you leave.

A month or more in Ireland. Buy an Irish prepaid SIM; at €20 for 28 days of unlimited data, it is the better deal. A little Pay-per-MB credit bridges the first hours after landing.

Ireland plus mainland Europe. Ireland is not part of the Torrum Europe regional plan, so pair an Ireland package with the regional one, as our Europe-wide route guide explains.

FAQ

Does my EU phone plan work in Northern Ireland?

Not by right. Since Brexit, “roam like at home” does not apply in the UK, so check whether your operator includes it.

Does a Torrum Ireland package work in Belfast?

No, it works on Irish networks only. For a short trip north, Pay-per-MB works on both sides; for longer, add a UK package.

Why did my phone switch to a UK network in Donegal?

Near the border, a phone can pick up a stronger UK signal. Pick eir or Three manually in the mobile network menu.

Do I need a UK ETA just to visit the Giant’s Causeway?

Most visitors do, including US, Canadian and EU citizens; British and Irish citizens are exempt. Nobody checks at the land border, but the rule applies.

Do I need ID to buy a SIM in Ireland?

There is no national registration law for prepaid SIMs, although a shop may ask for ID.

Can I buy a SIM at Dublin Airport?

Yes. Vodafone SIMs are sold at WHSmith in Terminal 1 and from vending machines in both terminals.

Which Irish networks does Torrum use?

eir and Three. You can choose between them manually if one is weak.

Will the 3G switch-off affect my phone?

Only if it cannot use 4G. eSIM phones support 4G in practice, so a phone that can take our eSIM is fine.

How do I find a B&B without a house number?

Use its Eircode, the seven-character postcode. Google Maps and Apple Maps both accept it.

Does my phone work on the ferry to Wales or France?

At sea it may connect to the ship’s satellite network, which can be expensive. Use airplane mode or the ferry Wi-Fi.

Do I need a visa for Ireland?

Not for a holiday on a US, Canadian, UK or UAE passport, according to Ireland’s May 2025 list; check ireland.ie before you travel. Ireland is outside Schengen and ETIAS.

I live in Ireland. Can I use Torrum at home?

No. Torrum is a roaming service for trips outside your home country, so residents need an Irish plan.

Final thoughts: decide before the border, not at it

In the Republic, the cities are easy and parts of the west need a coverage check, and Irish prepaid SIMs are cheap. The decision is mostly about trip length and about the border: a trip north brings in UK networks and a UK ETA.

On trips of up to 20 days, setting up an eSIM before you fly saves the most time, and one balance can follow you to Belfast. For a month or more, an Irish SIM is the better buy.

👉 Flying to Dublin, Shannon or Cork? Choose your Ireland eSIM.