Prepaid travel SIM: pick the right line, then keep it loaded
Roaming on your home number, a local prepaid SIM bought at the airport, or an international SIM you carry between trips — they behave very differently once you land. Here is the comparison, and how to put credit on whichever one you end up with, from anywhere.
Three ways to have a working phone abroad
Most travellers end up on one of these. They differ less in what they cost than in which number people can reach you on, and what happens to the line after the trip.
| Option | The number you use | Suits | The catch |
|---|---|---|---|
| Roam on your home SIM | Your usual one — nobody has to be told anything | Short trips, and anyone who cannot afford to miss a call or a bank code | Metered by your own operator at their roaming rates, which vary by destination |
| A local prepaid SIM bought at the destination | A new local number for the length of the trip | Longer stays, and heavy data use in one country | A second number to keep alive between trips, and your home line sits unused meanwhile |
| An international SIM you carry | One number that stays with you across several countries | Multi-country trips, and people who travel on a routine | Coverage and terms are set by whichever operator issued it — check before you rely on it |
Only the operator can tell you what a given SIM costs to use in a given country — rates and roaming terms are theirs, not ours. What is the same across all three is the part we handle: putting credit on the line.
Whichever line you carry, the top-up works the same
A top-up is addressed to a number, not to a card and not to a place. That one fact is what makes every awkward travel case solvable — and it is why the SIM you carry can be any of the three above.
It is also the limit of what we do. MobileTopUP adds credit to a prepaid line that already exists: there is no SIM to order here, nothing posted to your address and no eSIM profile to download. Buy the SIM from an operator or a seller at your destination, then use this page to keep it working — and because what arrives is credit to a number, whether that number sits on a plastic SIM or an eSIM changes nothing. The prepaid SIM overview covers the difference between the two.
Top up a number now- You can load a foreign SIM from your sofa at home, days before you fly.
- You can load your home number from the other side of the world, so it does not lapse while you are using a local SIM.
- The recipient side needs nothing at all — no app, no account, no code read out over a bad line. That matters when the phone is in a bag somewhere and you are not.
- The credit is applied by the operator on their own side, so the handset does not need mobile data or a Wi-Fi connection to receive it.
- Your card does not have to be issued in the destination country — the usual reason a local kiosk or an operator checkout refuses a traveller.
Which country do you pick at checkout?
The single thing travellers get wrong. The country field means the country the number belongs to — the one that issued the SIM. It is not where you happen to be standing, and it is not where you are flying next.
Spanish SIM, and you are in Spain
Pick Spain. The obvious case, and the only one where the two answers happen to match.
Spanish SIM, and you have moved on to Portugal
Still Spain. The SIM is a Spanish operator's; being in Portugal changes what the credit costs you to spend, not who you buy it from.
Home number, and you are in Japan
Pick the country that issued your home line. Japan is where you are; it has nothing to do with the top-up.
Not sure which country a number belongs to? Its international dialling code says so — a number starting +34 is Spanish however far it has travelled. Enter the number in full, with that code, and the network is worked out from it. The markets we cover are listed on the mobile top-up overview.
Calling home from a prepaid line
"International" gets used for two different things, and mixing them up is what produces a surprise bill.
Calling another country
Dialling abroad from the SIM. Operators price this per minute, and many sell an international calling plan or add-on that you buy out of the credit already on the line. Where an operator offers one, it shows up in that number's catalogue alongside airtime and data.
Using the SIM in another country
Roaming. A different charge, set by your operator for the country you are standing in, and it applies to calls, texts and data you use while there — including calls to numbers back at home.
We put credit on the line, including the operator's own calling plans where that operator sells them. We are not a calling provider: we do not carry the call, we do not set the per-minute rate, and we cannot quote one. Check the rate with the operator before you rely on it — and remember that a data bundle plus a messaging app is frequently the cheaper way to talk to people at home. Sizing a bundle is covered on mobile data bundles.
A trip, in three stages
Each one has a different job. The last is the one people skip, and it is the one that costs a number.
- 1
Before you fly
Put credit on the line you plan to land on, so it is live the moment the plane doors open. Write the number down somewhere that is not the phone itself, and check the SIM is not about to hit its expiry date.
- 2
While you are there
Top up from wherever you are, at whatever hour it is — no shop, no local card, no queue. If you have switched to a local SIM, this is also when to put a small amount on your home number so it does not quietly go dormant.
- 3
When you are back
The travel SIM goes in a drawer and the clock starts. Operators reclaim numbers that go unused for long enough, so a small top-up now and then is what keeps the same number waiting for your next trip.
How long a line survives without use is set by the operator, not by us — the prepaid SIM overview goes into how those windows work, and checking validity shows how to find out where a given line stands.
What goes wrong on the road
Four of them, and three are about which number you are actually looking at.
A dual-SIM phone shows two lines that look alike in a settings screen. Read the full number back against the country code before you pay: a Spanish SIM starts +34, a UK one +44. Getting it wrong sends real credit to a real stranger.
A SIM that has been idle since the last holiday may already have been deactivated or had its number recycled. If the operator refuses the top-up we refund in full and pass on the reason they gave — but you will still land without a working line, so test it before the trip, not at the gate.
The top-up itself does not travel over the internet — the operator applies it to the account at their end. Leaving data roaming off to avoid charges does not stop the credit arriving. Your emailed receipt and the operator's reference code are the confirmation either way.
Expired, blocked, roaming-only or moved to a contract — some SIMs are simply not eligible. The operator rejects those and the full amount comes back automatically. The delivery policy lists every case.
Travel SIM questions
Payment, refunds and account questions live in the help centre.
Open the help centreDo you sell prepaid international SIM cards?
No. There is no SIM to buy here and nothing is shipped — MobileTopUP only adds credit to a prepaid number that already exists. Buy the SIM from an operator or a seller at your destination, then come back here to keep it loaded.
Can I top up a foreign SIM before I leave home?
Yes, and it is the sensible order. Load it while you still have a good connection and the credit is waiting when you land, rather than depending on finding Wi-Fi in an arrivals hall.
Can I top up my home number while I am abroad?
Yes. Your card does not need to be issued in the destination country and you do not need to be in it either. This is how people stop a home line lapsing while they are away on a local SIM.
I am travelling through several countries. Which one do I choose?
The country that issued the SIM, every time. Moving between countries changes what the credit costs you to spend, not who sells it — a Spanish number is topped up as Spain whether you are in Madrid or Lisbon.
Does the phone need data or roaming turned on to receive a top-up?
No. The operator applies the credit at their end, so the handset does not need an internet connection for it to arrive. You get an emailed receipt with the operator's reference code regardless.
Will one SIM work in every country I visit?
That is the issuing operator's decision, not ours — coverage and roaming terms come with the SIM. Check them before you rely on one line for a whole itinerary. What we can say is that topping it up works from any of the countries we cover.
Guides for the network you end up on
Roaming setup on one side, the local prepaid brands travellers actually get handed on the other.
Roaming, before you go
Topping up a SIM you picked up abroad
Where to go next
This page is the traveller carrying the line. The neighbours cover the cases that are not that.
Never done one before? The six-step walkthrough runs from account to confirmed delivery, and the recharge routes compared weighs a browser against a shop, a voucher and an operator app.
Flying tomorrow? Load the line tonight.
Country, number, amount. Do it from home while the Wi-Fi is good and the credit is already there when you land.