What is Data-only plan?
Most travel plans work this way. App calls still work, but you get no local number and cannot receive SMS. If you need SMS one-time codes, keep your main SIM enabled alongside it.
A data-only plan gives you internet and nothing else. No phone number comes with it. In practice that means you are fully connected — maps, ride-hailing, hotel bookings, messaging, video calls all work — but no local number exists for anyone to ring, and the plan cannot receive SMS. This is how most travel plans on the market are built, and it is something to understand before buying rather than while standing in an arrivals hall.
This page covers what still works normally, what does not and is easily overlooked, how to handle one-time codes sent to your existing number, what to do if you genuinely need a local number, and how to judge how much data to buy. The details differ by provider and by country, so we quote no figures on anyone's behalf — but we will set out everything worth checking.
Why most travel plans are built this way
Handing a subscriber a phone number is not a matter of flipping a switch. It involves number allocation inside that country, subscriber registration under that country's rules, and interconnection with local voice systems — each carrying costs and legal conditions that differ from place to place. Providing data alone is far simpler to arrange across many countries at once, so travel plans usually take that route.
For most travellers the limitation barely registers, because what a trip actually needs is internet rather than a local number: the people you talk to are already on messaging apps, and hotels and restaurants take bookings online. The real friction shows up in only two places — receiving SMS one-time codes, and calling a local number that offers no online alternative — and both can be planned around in advance.
| What you need to do on a trip | Does a data-only plan cover it? | Note |
|---|---|---|
| Maps, navigation, ride-hailing | Yes, normally | All of it runs over the internet and needs no number |
| Messaging and video calls in apps | Yes, normally | The other person needs the same app and to be online |
| Taking calls on your existing number | Not from this plan | You need your home SIM active alongside, or a service from your home operator |
| Receiving bank SMS one-time codes | Not from this plan | The code goes to your existing number, so that line has to be on |
| Calling a local number such as a hotel or taxi | Not directly | Many can be reached by app or email; if a real call is unavoidable, plan for it in advance |
| Sharing a hotspot with another device | Usually, but check that plan's terms | Some plans restrict sharing, so check first if you need it |
The two rows that actually bite are SMS and calling local numbers; the rest feels no different from home
Everything that still works exactly as usual
A traveller's day is mostly opening maps, looking up somewhere to eat, booking tickets, checking email, sending photos home and watching something in the evening. All of that is pure internet use, so a data-only plan carries it with no adjustment at all. Day to day it feels the same as being at home; only the network name at the top of the screen has changed.
App calling belongs in the same category. If the people you need are on the same app, you can reach them by voice or video without any local number, and plenty of families run an entire trip this way without feeling short of anything. The one caution is that video calls consume more data than most people expect, so if you plan long daily calls, allow for that when choosing the plan.
What it cannot do, and what people overlook
The first is SMS of any kind. A data-only plan has no number, so there is nowhere for a message to land. When a bank, a government app or any other service sends a verification code to your existing number, it goes to your home SIM, never to the travel eSIM. People who remove the home SIM before flying, worried about roaming charges, usually meet this on day one when they try to move money or check in online.
The second is calling a local number with no online equivalent: a small guesthouse that arranges key collection a restaurant that confirms bookings by voice, a driver who rings you at the meeting point. If your trip contains any of that, arrange a fallback beforehand — ask the accommodation for a chat channel at the time of booking, or line up someone who can make the call for you.
Setting the home SIM and the eSIM to work together
The sequence below is what we suggest doing before every trip. It takes little time and removes two problems at once: codes you cannot receive, and a roaming bill you did not expect. Menu names differ between brands, so look for what a setting does rather than for the exact wording.
- 1Install the eSIM profile while still at homeDo it on a connection you trust, then activate according to the plan's terms. If validity starts at first connection, install now but leave activation until you land.
- 2Set the eSIM as the data lineIn the phone's SIM settings, pick the eSIM profile as the line for mobile data. This is the switch that sends every app through the travel plan instead of the home line.
- 3Turn off data roaming on the home SIMLeave the home line active for calls and messages, but disable data while roaming on that line. Without this the phone can slip back onto the home line's data at moments you will not notice.
- 4Stop automatic updates and backups over mobile dataApp stores, cloud sync and photo backup are the leading causes of an allowance vanishing without explanation. Restrict them to Wi-Fi before you leave.
- 5Test the whole arrangement before boardingHave someone call and text your usual number once to confirm the home line still receives, then load a web page to confirm data is flowing through the line you selected.
Sorting out one-time codes before you go
One-time codes trip up more journeys than any other limitation, because they do not bother you while sightseeing — they bother you at the moment you need to pay for something or get into an important account. The most direct fix is keeping the home SIM on to receive messages, as described above. If for some reason you cannot, deal with it before departure rather than at the destination.
A common alternative is switching the important accounts to a verification method that does not rely on SMS at all, such as approval inside the provider's own app or a code-generator app. Every service offers something different and a few still insist on SMS, so go through them one by one at least a week ahead — changing a verification method sometimes involves a waiting period.
If you genuinely need a local number
Some trips really do benefit from a local number: a long working stay, a car rental that verifies or dealing with an office that only takes voice calls. In those cases what you are looking for is a plan that explicitly includes voice and messaging, not an ordinary data plan — and it is worth checking that country's subscriber registration rules too, since some require identity verification before a number can be activated.
If you are unsure whether your trip qualifies, run through the coming fortnight and ask who would have to reach you with no other option. If the answer is nobody, a data-only plan is enough. If there are two or three and they matter, arrange a fallback in advance — or ask us what options exist for the destination you are heading to.
Emergency calls need their own preparation
Calling an emergency number abroad depends on the handset you carry, that country's rules, and the network answering in the area — it is not something a data plan can guarantee on your behalf. The prudent step is to note the destination's emergency numbers both in the phone and on paper, along with your accommodation's address in the local language, so you can give a location even when tapping through screens is not practical.
Keeping the home SIM active helps here as well, since the phone retains an attachment to the local mobile network. Even so, do not treat it as a guarantee that holds everywhere. Ask your operator and read the destination's own guidance before you travel, particularly if you are heading somewhere remote or travelling alone.
How much data is enough
With no number to fall back on, data is the whole trip, which makes a realistic estimate more important than usual. The method that works is to reason from your own habits rather than from a round number you once heard. Think about how long the map stays open in a day, whether you watch video, how many minutes of video calls home you make, and whether another device needs the hotspot. Those four points decide nearly everything.
| Usage pattern | What consumes the most | What to do before you go |
|---|---|---|
| Ordinary city travel, mostly maps and messaging | A map left open all day and images loading in social apps | Download that city's offline map in advance |
| Working while travelling with frequent online meetings | Video calls and files syncing to the cloud | Restrict syncing to Wi-Fi and leave headroom for meetings |
| Family travel sharing one connection | Every device on the hotspot draws from the same pool | Check the plan permits sharing and budget for all devices together |
| Long trips of several weeks | Cumulative use plus app updates that slip through now and then | Choose a plan you can top up and check the balance periodically |
When the estimate is borderline, buy more headroom than you think, because topping up on a busy day costs the most time
The pre-departure checklist
These six cover nearly everything people run into with a data-only plan. Clear them before departure and the rest is just ordinary use.
- Confirmed the handset supports eSIM and is not network-locked
- Installed the profile while still at home
- Set the eSIM as the data line and switched off the home line's data roaming
- Left the home SIM on for calls and SMS, one-time codes especially
- Downloaded offline maps and travel documents onto the phone
- Estimated the data for the whole trip with headroom for hotspot sharing
The problems that show up on day one
The most common symptom is a profile that installs but produces no internet, and almost always the cause is the order of the settings rather than the plan itself. Work through it in sequence: pick the correct line for data, enable roaming on the eSIM profile as the plan's instructions specify, try selecting the network manually, then restart the phone. If all four are done and it still will not connect, get in touch.
The next most common is an allowance draining faster than expected in the first days, usually from automatic photo backup or app updates still permitted on mobile data. Check those two settings first, then look at the per-app usage figures on the handset, which normally identify the culprit within seconds.
If you are still unsure, ask before buying
The questions we answer fastest are the ones asked before purchase, because at that point everything is still changeable. If you are unsure whether the plan you are looking at includes voice and SMS, whether your handset will work, or whether the allowance suits your trip, just ask. Tell us the destination, the number of days, the handset model and roughly how you use your phone, and that is enough for a direct answer.
Our channels are LINE at https://lin.ee/skDPoNx (@esimonline), email at esimonline.asia@gmail.com, and phone at 089-942-0818 or 088-521-6848. We take messages around the clock, every day, though replies can run a little slower late at night Thailand time, and deeper cases such as refunds or supplier checks take longer than quick ones like resending a QR code. If yours is urgent because you are about to board, say so at the top of the message so it can be prioritised properly.
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Can I call my hotel on a data-only plan?+
Not directly to a local number, because the plan carries no voice service. Most accommodation can be reached by email, a chat app or the messaging system of the platform you booked through. If yours only takes phone calls, ask for a chat channel at the time of booking or arrange someone who can call on your behalf.
How do I receive bank one-time codes while abroad?+
Codes always go to your existing number, so keep the home SIM active to receive messages while switching off its data roaming to avoid unintended charges. The alternative is moving important accounts to a verification method that does not use SMS, which is best done at least a week before you travel since some services impose a waiting period.
Why does the plan come without a number?+
Because issuing a number in any country involves number allocation, subscriber registration under local rules, and interconnection with local voice systems, all of which vary from place to place. Data alone is far simpler to deliver when one plan has to work across many countries, which is why most travel plans on the market are built this way.
Can I use an app to call instead, and will it sound acceptable?+
Yes, and the quality depends mainly on how steady the connection is at that moment: good where the signal is strong, choppy where it is weak or heavily shared. The bigger constraint is that the other person must be on the same app, so agree on that with the people who matter before you travel.
What if I want both data and a local number?+
Look for a plan that explicitly includes voice and messaging rather than an ordinary data plan. Availability differs by country, and some countries require identity verification before a number can be activated. Tell us the destination and dates and we can look at what options exist.
Does leaving the home SIM on mean roaming charges?+
Leaving a line switched on to receive calls and messages is not the same thing as using data while roaming. The terms and charges belong to the operator that issued your number, so ask them plainly before you travel and keep the answer in writing. What you should certainly do is disable data roaming on the home line and let the eSIM carry all the data.