eSIM or international roaming: what actually matters for Indian travellers

The real question is not which is cheaper. It is whether your Indian number stays reachable for bank OTPs while your data runs on something else — and that depends on your handset, not your plan.

The question people should be asking

Most comparisons of eSIM against roaming argue about price. That is the least interesting variable, because both have become cheap enough that the difference over a ten-day holiday is rarely decisive.

The question that actually matters to an Indian traveller is this: while I am using cheap local data abroad, does my Indian mobile number stay reachable for the one-time passwords my bank, my airline and UPI will send me?

Get that wrong and you can find yourself unable to authorise a card transaction in a foreign restaurant because the OTP went to a number that is switched off. Get it right and everything else is detail.

What an eSIM actually is

An eSIM is a SIM profile written into a chip already inside the phone, rather than a plastic card you insert. Functionally it is the same thing — an identity on a mobile network — but you install it by scanning a QR code or through an app, which means you can buy a foreign network's plan from your sofa in Delhi and have it ready before you land.

Two consequences follow. You do not have to find a shop at the destination airport, queue, and hand over your passport, which is the part of arrival most people find tiring. And you do not have to remove your Indian SIM, which is exactly the thing that used to break OTPs.

Most travel eSIMs are data-only. They give you internet, not a local phone number for calls and texts. For almost all travellers that is fine, because calls now happen over WhatsApp and data anyway — but it is worth knowing that you are not buying a phone number.

Whether your phone can actually do it

Two conditions have to be true, and the second catches people out more than the first.

Your handset must support eSIM. Broadly, recent iPhones and recent flagship Android phones do; budget Android models and older devices frequently do not. Check your specific model rather than assuming, because this varies by model and sometimes by the region the phone was sold in.

And your handset must be carrier-unlocked. Apple states the requirement plainly for Dual SIM: the iPhone must be unlocked, or both cellular plans must come from the same carrier. A phone bought on a carrier contract and never unlocked will refuse a foreign eSIM regardless of how good the plan is.

Check both weeks before you travel, not the night before. Unlocking is usually a request to your carrier, and it is not always instant.

Keeping your Indian number alive for OTPs

This is the section worth reading twice. On a dual-SIM phone you can run a travel eSIM for data while your Indian SIM stays installed and registered, so SMS one-time passwords still arrive. That is the configuration most travellers want.

But your Indian SIM only receives that SMS if it is connected to a network abroad — which means international roaming has to be active on it, even if you never use it for data. Many people disable roaming entirely to avoid bill shock, and then wonder why the bank OTP never came.

The practical setup: keep the Indian line active with roaming enabled for incoming SMS, disable mobile data on that line so it cannot quietly consume an expensive roaming allowance, and set the travel eSIM as the data line. Most carriers sell a low-cost incoming-SMS or minimal roaming pack precisely for this.

Know the limits of the hardware too. Apple notes that an iPhone uses one cellular data network at a time, and that while you are on a call on one line the other shows no service unless Wi-Fi Calling is switched on. If you expect calls on your Indian number, enable Wi-Fi Calling before you leave.

When roaming is genuinely the better choice

Short trips. For three or four days, the effort of buying, installing and configuring an eSIM can exceed the money saved, and a carrier day-pack is simply less to think about.

Phones that cannot take an eSIM, or that are carrier-locked, where roaming is the only option that works at all.

Trips where you must keep your Indian number for voice — some business travel, and anyone whose work calls arrive on that number.

Multi-country trips with awkward coverage, where a single roaming plan that follows you across borders can be simpler than juggling regional eSIM plans. Many travel eSIMs do sell regional coverage, but the exact country list is the thing to check rather than assume.

And travellers who are simply not comfortable troubleshooting a network setting in an airport. That is a legitimate reason and not a technical failing.

When eSIM is clearly better

Longer trips, where the per-day cost difference compounds. Data-heavy travel — maps, translation, ride-hailing and uploads all day. And any trip where you would otherwise ration data, because rationing is where the real cost of roaming shows up: the wrong turn you took because you did not want to open maps.

It also suits travellers who want the connection working the moment the plane doors open, rather than after finding a shop that is open at the hour you landed.

Two practical examples. In Japan, coverage is excellent nationwide and an eSIM installed before departure means transport apps work from the airport train onward. Across Europe, a regional eSIM covering multiple countries avoids buying a new local SIM every time you cross a border on a rail itinerary.

Setting it up without stress

Buy and install before you fly, while you are on reliable Wi-Fi. Installation writes the profile to the phone; it does not usually start the plan, which begins when you connect abroad or on a stated date. Read which of those applies to the plan you bought.

Label your lines in settings — "India" and "Travel" — so you are not guessing under pressure. Set the travel line as default for data and the Indian line as default for calls and messages.

Keep the QR code or activation details saved somewhere you can reach without mobile data. A screenshot in your photo library and an email you can open over Wi-Fi are both fine; a code that only exists in an app that needs data to load is not.

Do not delete your Indian eSIM profile to make room, if your phone stores profiles that way. Removing it can require your carrier to reissue it, which is a slow thing to discover abroad.

When it does not work

No data after landing: check that the travel line is enabled, that data roaming is switched on for that line specifically — travel eSIMs generally require it, since they are roaming on a partner network — and that the line is selected as the data line.

OTPs not arriving: the Indian line is not registered on a network. Confirm roaming is enabled on that line and that it shows a carrier name rather than no service.

Hotspot not working: some travel plans exclude tethering, and some phones disable it on a secondary line. Check the plan terms before you rely on it for a laptop.

And keep one fallback: airport, hotel and café Wi-Fi still exist. Being unreachable for an hour is an inconvenience, not an emergency, provided somebody at home knows your itinerary. Our travel guides cover the rest of the pre-departure list.

Sources

• Using Dual SIM with an eSIM — unlock requirement and line behaviour — Apple Support
• Use eSIM while travelling internationally with your iPhone — Apple Support