How your phone works in another country
Roaming is when your phone uses another operator's network, usually in another country where your own network does not reach. The local network checks your SIM with your home operator, carries your calls, texts and mobile data, and sends the bill to your operator. Mobile data used this way is called data roaming. In the European Union you pay what you pay at home until 2032, a rule called roam like at home; elsewhere, and for most UK customers in the European Union, operators charge extra. The rules change often: we last checked every fact on this page on 30 October 2026.
Purple: your phone's trafficKey
- Purple: your phone's traffic
- Dashed: radio
Roam like at home · you pay what you pay at home
Press a button, or click your mobile, the house or the gateway.Press a button, or tap your mobile, the house or the gateway.
The network works the same way in both. Roam like at home covers a SIM from a European Union country used in another one, and in Norway, Iceland, Liechtenstein, Ukraine and Moldova.
Anatomy of roaming: your mobile on holiday, the local mast and operator, the international link across the border, and your home operator's register and data gateway. The toggle above it shows the same network with roam like at home or with roaming charges. The drawing is not to scale.
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Follow one call
Press Play to watch the call, or scroll down and the drawing follows you one step at a time. Try it, under the drawing, makes your own call.Press Play to watch the call, or Next to go one step at a time. Try it, under the drawing, makes your own call.
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Step 1 of 5
You land and switch on your phone
Your phone looks for your own network and cannot hear it. It hears the masts of the local operators instead, and it picks one your operator has an agreement with. Your SIM tells the local network who you are with a number of up to 15 digits. The first three name your country and the next two or three your operator. That is all the local network needs to know where to ask about you.
Why does my phone pick one local network and not another?
Your operator decides most of it. It usually has agreements with more than one operator in the same country, and it keeps a list of the networks it prefers on your SIM. Your phone tries those first. The standard calls this steering of roaming.
Near a border the same thing can happen at home. If a mast across the border is stronger than your own, your phone may roam without leaving your country. European Union law tells operators to protect you from those charges and to explain how to avoid them.
Sources: ETSI TS 123 122: how a phone picks a network, and steering of roaming (2026); GSMA: International roaming explained (2012); EUR-Lex: Regulation (EU) 2022/612 on roaming on public mobile communications networks within the Union (2022)
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Step 2 of 5
The local network asks your operator about you
The local operator has never seen your SIM. Its visitor register sends a question over the international link to your operator's home register: is this SIM genuine, and what may it use? Your home register answers and notes which network you are now in. The visitor register makes a guest entry for you, and your phone can call and go online. Then a text arrives with the prices that apply to you.
How can a network check a SIM it has never seen?
It borrows the check from your home operator. On 4G the local network first asks your home register for the information it needs to test your SIM, then tells it where you are. In return the home register sends your subscription details: calls, data, what is barred.
From then on your home register keeps the address of the network you are in. That is how a call to your number finds you later.
In the European Union the law requires the welcome text. Your operator must tell you, free of charge, what calls, texts and data cost where you are, and that 112 reaches the emergency services.
Sources: ETSI TS 129 272: the 4G network's questions to the home register (2026); ETSI TS 123 012: location management in mobile networks (2025); EUR-Lex: Regulation (EU) 2022/612 on roaming on public mobile communications networks within the Union (2022)
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Step 3 of 5
A friend calls you from home
Anna dials your usual mobile number. The number belongs to your operator, so the call goes to your operator first, wherever you are. Its switch asks your home register where you are. The register asks the local network for a roaming number, a temporary number that starts with the code of the country you are in, and the switch sends the call across the border to it. The local network then rings your phone, as it would ring any phone in its own cells.
What if someone in the same country as me calls me?
Their call usually travels to your home country and back, because only your operator can find you. The standard has a shortcut that keeps the call in the country, called optimal routeing, but it works only when every network on the way supports it.
Do you pay to take the call? In the European Union, no. Taking calls while roaming costs nothing extra there. Outside it, your operator may charge you for every minute you receive.
Sources: ETSI TS 123 018: basic call handling in mobile networks (2025); ETSI TS 123 003: numbering, addressing and identification (2026); ETSI TS 123 079: optimal routeing of calls to roaming phones (2025); EUR-Lex: Regulation (EU) 2022/612 on roaming on public mobile communications networks within the Union (2022)
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Step 4 of 5
You open a map, and your data goes home first
Your phone sends its request to the local mast. The local operator does not send it to the internet. It wraps it and hands it over the international link to your operator's data gateway, and only there does it leave for the internet. The answer comes back the same way. The standard calls this home routing. It also allows the local operator to send your data straight out, called local breakout, when your operator agrees. A call over 4G can go home the same way, as data.
Should data roaming be on or off?
Data roaming is the switch on your phone that lets it use mobile data on a network abroad. In the European Union, under roam like at home, leaving it on costs what your data costs at home, up to your operator's fair use limit.
Outside the European Union your operator sets the price, so check your plan before you go, or keep it off and use Wi-Fi. If your SIM is from the European Union, the law makes your operator stop your data there, by default once you reach close to €50 a month before VAT, unless you choose to carry on.
Switch it off on a ferry or a plane. Their networks reach land by satellite, and roam like at home does not cover them. In summer 2025 their data cost an average of €149 a gigabyte.
Sources: ETSI TS 123 401: the 4G network and its roaming architecture (2026); GSMA IR.88: roaming guidelines for 4G networks (2021); EUR-Lex: Regulation (EU) 2022/612 on roaming on public mobile communications networks within the Union (2022); BEREC: 32nd report on international roaming benchmark data (2026)
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Step 5 of 5
The bill goes home too
The local operator records every call, text and megabyte you used and sends the records to your operator through a clearing house, in files called TAP. Your operator pays the local one the price they agreed, and in the European Union the law caps its average: €1.10 a gigabyte of data in 2026, and €1 from 2027. You never pay the local operator. Your operator bills you: in the European Union what you pay at home, and elsewhere its own roaming charges.
Is roam like at home unlimited?
No. It is meant for trips. It is not for someone who lives in one country and uses a cheaper SIM from another country all the time. Your operator may look at your use over at least four months. If you spent more time abroad than at home and used more abroad than at home, it may ask you to explain within 14 days before it charges extra.
With an unlimited or very cheap data plan, your operator may also set a data limit for roaming. It must be at least twice what your monthly price would buy at the wholesale cap: on a plan of €13 a month before VAT, at the 2025 cap of €1.30 a gigabyte, at least 20 GB.
Sources: GSMA: Transferred Account Procedure, standardised interfaces (2026); EUR-Lex: Regulation (EU) 2022/612 on roaming on public mobile communications networks within the Union (2022); EUR-Lex: Commission Implementing Regulation (EU) 2016/2286 on fair use policy (2016); Your Europe: Mobile roaming costs (2026)
Roaming in numbers
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€1.15
In 2006 a roaming call in the European Union cost an average of €1.15 a minute, more than five times what the operators paid each other for it.
European Commission: Press release IP/06/978 on cutting roaming charges (2006)
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17 times
In summer 2019, people roaming in the European Union used 17 times as much mobile data as in summer 2016, the last summer before roam like at home.
European Commission: Press release IP/21/653 on extending roam like at home (2021)
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€149
On ships and planes, where roam like at home does not apply, mobile data cost an average of €149 a gigabyte in summer 2025.
BEREC: 32nd report on international roaming benchmark data (2026)
How it came to be
- 1982
One phone for Europe
The European conference of telecoms administrations sets up the Groupe Spécial Mobile, GSM, to design one mobile technology for the whole of Europe.
- 1992
The first roaming agreement
Telecom Finland and Vodafone UK sign the first international roaming agreement, so each one's customers can use the other's GSM network.
- 2007
A price cap for calls
The European Union sets its first price cap: a roaming call may cost at most €0.49 a minute to make and €0.24 a minute to receive, before VAT.
- 2017
Roam like at home
From 15 June, operators may no longer charge extra for calls, texts and data in another European Union country.
EUR-Lex: Regulation (EU) 2015/2120 on open internet access and retail roaming charges (2015)
- 2021
The United Kingdom leaves
From 1 January the rule no longer covers the United Kingdom. Most UK operators then bring in a daily charge for the European Union.
Ofcom: Mobile roaming, strengthening customer protections, statement (2024)
- 2022
Ten more years
A new regulation keeps roam like at home until 30 June 2032 and adds the right to the same network quality abroad, 5G included where the local network has it.
- 2026
Ukraine and Moldova join
From 1 January, roam like at home also covers trips from the European Union to Ukraine and Moldova.
Arcep: Prix des appels, SMS et internet mobile en Europe (2026)
What the rules say
Who pays what abroad depends on where your SIM comes from and where you are. The European Union has one rule for all its countries; the United Kingdom and Switzerland have their own.
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European Union: the price you pay at home
Your operator may not charge you extra for calls you make or take, texts or data in another European Union country, or in Norway, Iceland, Liechtenstein, Ukraine and Moldova. It must give you the same network quality as at home where the local network has it, 5G included. The rule runs until 30 June 2032. Each country's regulator explains it: Arcep in France, the Bundesnetzagentur in Germany, the Authority for Consumers and Markets (ACM) in the Netherlands, the Belgian Institute for Postal Services and Telecommunications (BIPT) in Belgium.
EUR-Lex; European Commission; Arcep; Bundesnetzagentur; ACM ConsuWijzer; BIPT
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European Union: fair use
The rule is for trips. An operator may ask for proof that you live in its country, watch your use over at least four months, and charge a small surcharge, after a warning, if you are mostly abroad. On unlimited or very cheap data plans it may set a roaming data limit, never below what the law's formula gives. The step on the bill has the details.
EUR-Lex (1, 2); Your Europe
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Outside the European Union: warnings and a cut-off
With a SIM from the European Union, roaming elsewhere has no price cap, but your operator must still text you the prices when you arrive and stop your mobile data once you reach a limit close to €50 a month before VAT, unless you choose to go on. It must also let you opt out of the networks on ships and planes.
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United Kingdom: daily charges and alerts
Since 1 January 2021, UK operators set their own prices for the European Union, and most charge a daily fee: £2 to £2.30 a day in February 2024. O2 is the exception among the large ones, with up to 25 GB in the European Union at no extra cost. Since 1 October 2024, Ofcom's rules make operators tell you when you start roaming what it will cost and how to limit your bill.
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Switzerland: billed to the second and the kilobyte
Switzerland is outside the European Union rule, and its operators set their own roaming prices. Since 1 July 2021 Swiss law makes them bill roaming to the exact second and kilobyte, set a cost limit when you sign the contract, and keep roaming on ships, planes and satellites off unless you switch it on. If you travel to Switzerland with a SIM from the European Union, that means your own operator sets the price there.
Federal Office of Communications (BAKOM); European Commission; Fedlex
These are the floors the law sets. A plan can give you more: some operators in the European Union include the United Kingdom or Switzerland at no extra cost, so check yours before you travel.
Where Voxbi fits
Voxbi, a cloud phone system hosted in the European Union, puts your business number in an app on your mobile, so abroad you can make and take office calls over Wi-Fi or mobile data, and Mixvoip, which owns Voxbi, provides the numbers.
See it in Voxbi