Should you use an eSIM, international roaming or a local SIM abroad? Start by checking your existing mobile plan. If it includes your destination with enough data, roaming is often the simplest choice. If it doesn't, a travel eSIM lets you arrange data before departure. For a longer stay or a local phone number, compare local SIM offers as well.
The right option is not necessarily the one with the lowest advertised price. Compare the cost for your full trip, the data you actually need and whether you must receive calls or texts on a particular number. This guide shows when each option wins and where travellers can get caught out.
Use the table below for a quick comparison, then check the examples and setup advice before buying.
eSIM vs roaming vs local SIM: quick comparison
| Feature | Travel eSIM | Home-network roaming | Local SIM |
|---|---|---|---|
| Setup | Usually installed digitally before travel | Uses your existing SIM and plan | Usually purchased and activated locally |
| Cost | Often competitive for international data | Can be included or expensive | Can offer excellent local value |
| Keep your usual number | Yes, on compatible dual SIM devices | Yes | Depends on your phone's dual SIM support |
| Calls and SMS | Many plans are data-only | Uses your existing number, subject to roaming terms | Often available with local plans |
| Multiple countries | Regional plans are available | Depends on your roaming agreement | Depends on the local plan |
| Main drawback | Requires a compatible, unlocked phone | Potential roaming charges | Purchase and registration can take time |
Option 1: Using your existing SIM with international roaming
Roaming allows your normal mobile provider to connect your phone to a partner network in another country.
You keep your existing phone number and usually don't need to install anything new. Once you arrive, your phone can connect to an available partner network, provided international roaming is enabled on your account and device.
The main advantage is convenience. The main disadvantage is that the price can vary dramatically.
Some mobile plans include roaming in selected countries at no additional charge. Others offer a daily travel pass, while some charge separately for calls, texts and data.
When roaming is the best choice
- Your existing plan includes your destination and enough data for your trip.
- You're travelling for only a day or two and a roaming pass is reasonably priced.
- You need your normal number for conventional calls and SMS.
- You don't want to install or manage another SIM.
When roaming becomes expensive
Imagine your provider charges £6 per day to use your phone abroad. Over a 14-day holiday, that could cost £84 if the charge applies every day.
A separate travel eSIM might cost considerably less for the mobile data you need. However, if your home plan already includes roaming, buying another plan could be an unnecessary expense.
The £6 daily charge is an example, not a current tariff. Before travelling, check the price for your destination, the roaming data cap and exactly what triggers a daily fee.
Option 2: Buying a local SIM card abroad
A local SIM connects you through a mobile provider operating in your destination country.
You can often buy one from an operator's shop, airport counter or authorised retailer. Depending on the country, you may need to present a passport or other identification to register it.
Local plans can offer generous data allowances and may include a local phone number, domestic calls and SMS.
When a local SIM makes sense
- You're staying in one country for several weeks or months.
- You need a local phone number for calls, bookings or other services.
- A local operator offers better value than available travel eSIMs.
- You don't mind visiting a shop and completing any registration requirements.
What are the disadvantages?
You may need to find a shop, wait for registration and configure your phone after arrival. Airport SIM packages aren't necessarily the cheapest local option either.
If your phone has only one active physical SIM slot, replacing your home SIM may also interrupt access to your usual number until you switch back.
And a local SIM is not automatically cheaper than an eSIM. For a short holiday, a competitively priced travel eSIM could cost less than an airport tourist package.
Option 3: Using a travel eSIM
A travel eSIM is a mobile plan you download digitally onto a compatible phone. There's no physical card to insert, and many providers deliver installation details immediately after purchase.
You can often install the eSIM before departure, then select it for mobile data when you reach your destination.
For example, if you're travelling from the UK to Thailand, you could purchase a Thailand eSIM before your flight and use it for navigation, messaging and transport bookings after landing.
Why travellers choose eSIMs
- Buy and install a plan without visiting a phone shop.
- Compare prices and data allowances before travelling.
- Keep your existing SIM installed on a compatible dual SIM phone.
- Choose regional packages for trips involving multiple countries.
- Avoid relying on potentially expensive home-network data roaming.
What are the disadvantages?
Your phone must support eSIM and be network-unlocked. Some regional device versions don't support eSIM even when similarly named models do.
Many travel eSIMs are also data-only. They provide internet access but don't include a traditional phone number, calls or SMS.
Finally, not every eSIM is reusable. Some providers support adding data to an existing profile, while others require a new eSIM when the original plan expires.
Which option is actually cheapest?
Start with what you already pay for. Included roaming can be the cheapest option because it adds no extra charge. When roaming costs £6 per day, a separately priced travel eSIM deserves a look. On a longer stay, compare local operator packages with long-validity travel eSIMs rather than assuming either is cheaper.
Consider these illustrative examples:
| Travel situation | Option worth checking first | Why |
|---|---|---|
| Weekend in a country included in your mobile plan | Existing roaming | You may already have sufficient data at no extra cost |
| Seven days abroad with expensive roaming charges | Travel eSIM | A separate data package could cost less |
| Six weeks in one country | Local SIM and travel eSIM | Compare long-validity packages and local offers |
| Visiting several European countries | Regional eSIM or included roaming | One plan may cover multiple destinations |
| Need a local number for regular calls | Local SIM or voice-enabled eSIM | Data-only packages won't meet that requirement |
When comparing costs, look beyond the headline price. A 5GB package valid for seven days isn't equivalent to a 20GB package valid for 30 days.
Check the total allowance, validity period, included countries, network access, speed restrictions and whether you can add more data if needed.
Can you keep your normal number while using a travel eSIM?
Yes, on many modern dual SIM phones. You can keep your home SIM active for calls and texts while using a travel eSIM for mobile data.
For example, you could receive SMS verification codes on your UK number while browsing the internet through a separate travel eSIM.
However, your home provider's roaming charges can still apply to certain calls, texts and other services. Receiving verification codes also depends on your home line remaining active and supporting SMS roaming in the destination.
Before travelling, make sure the travel eSIM is selected for mobile data and check that automatic mobile data switching won't unexpectedly use your home line.
Do you need a local phone number when travelling?
Not necessarily. Many travellers can manage with a data-only plan because WhatsApp, maps, email, booking apps and internet messaging services work over mobile data.
You can normally continue using your existing WhatsApp number even when your internet connection comes from a different eSIM.
A local number becomes more useful if you need to make conventional domestic calls, receive local SMS messages or register for a service that specifically requires a local number.
If that matters, check the plan's calling and SMS features before purchasing. Don't assume every travel eSIM provides a phone number.
What about coverage and internet speed?
An eSIM isn't inherently faster or slower than a physical SIM. Both use mobile networks, and the connection you experience depends on the operator, available technology, signal strength, congestion and plan restrictions.
Travel eSIM providers sometimes connect through different local networks within the same country. Two packages for the same destination can therefore offer different coverage and performance.
A local SIM from a major network might provide better access in some locations, but that isn't guaranteed. Equally, an eSIM using a strong local partner network can perform very well.
For remote areas, rural road trips or destinations with limited coverage, check the actual supported networks rather than choosing solely on price.
What if you're travelling to several countries?
For a trip crossing several borders, a regional eSIM can save you from arranging a new SIM in each country. First check whether your existing roaming plan already covers the full route.
Buying a separate local SIM in every destination can become inconvenient. A regional eSIM may allow you to use one package across several countries, while your home provider might also offer a roaming allowance covering the entire itinerary.
For example, someone travelling through France, Italy and Spain could compare a Europe eSIM against their existing European roaming benefits rather than buying three individual country plans.
Check the full country list carefully. A regional package doesn't necessarily include every country in that region.
How to choose the right option for your trip
Answer these five questions before paying. They will narrow the choice much faster than comparing dozens of packages without a plan.
- Is roaming already included? Check your mobile provider's current charges and allowances for every destination.
- How much data do you need? Think about maps, messaging, social media, video calls and streaming.
- Does your phone support eSIM? Check your exact model and whether it's network-unlocked.
- Do you need a local number? A data-only travel eSIM may be sufficient, but not for every situation.
- How many countries are you visiting? A regional package may be more convenient than separate plans.
If your phone is locked, check how to tell whether your phone can use a travel eSIM before buying. If it is compatible, compare the final price, data allowance, expiry date and supported networks for the options on your shortlist.
Frequently asked questions
Is an eSIM cheaper than international roaming?
It often can be when your home provider charges daily roaming fees or expensive data rates. But if your mobile plan already includes roaming at your destination, using your existing SIM may cost nothing extra.
Is a local SIM cheaper than a travel eSIM?
Sometimes, particularly for longer stays or large data allowances. However, short-term travel eSIM packages can be competitive, and airport tourist SIMs aren't always the cheapest local option.
Can I use an eSIM and my normal SIM at the same time?
Many modern phones support dual SIM functionality. You can often use your home line for calls and SMS while selecting a travel eSIM for mobile data. Check your device's supported SIM combinations.
Does a travel eSIM avoid all roaming charges?
No. It can help you avoid home-network data roaming charges if your mobile data is correctly configured to use the travel eSIM. Your home SIM may still incur charges for certain calls, texts or other services.
Can I buy a travel eSIM before leaving home?
Yes. Many providers deliver eSIM installation details digitally. Check the activation policy before installing, because some plans start their validity period immediately upon installation.
Compare travel eSIM plans before you go
For some travellers, the simplest option is to keep using their existing mobile plan. For others, a local SIM provides the best value. But if you want mobile data arranged before departure, a travel eSIM is well worth comparing.
Compare travel eSIM plans on eSIM Indexer by destination, allowance, validity and price. Then compare the result against your home provider's roaming charges and any local SIM offers. You don't need to buy an extra plan if your existing one already does the job.
Editorial note: Prices, roaming allowances, activation policies and network access can change. The examples here illustrate how to compare options and are not live quotations. Confirm plan terms and device compatibility with the relevant provider before purchasing.
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