Telefónica’s O2 Spain has turned the travel eSIM into a very practical summer perk. The operator is promoting eSimFLAG, the Movistar-backed travel eSIM service, to existing O2 customers through the Mi O2 app. The headline offer is simple: unlimited data in covered international destinations for €2.45 per day.

That price matters because it is not positioned like a classic roaming add-on, with destination tables, usage anxiety and small print that only becomes interesting when the bill arrives. It feels closer to a digital travel extra. Open the app, choose the destination and travel days, install the eSIM, and use data abroad without swapping your physical SIM or losing your main number.

O2’s own promotion page describes eSimFLAG as a travel eSIM brand designed to connect people abroad immediately, simply and without surprises. The current offer is aimed at O2 Spain customers and is accessed through the “Destacados” section of Mi O2. O2’s legal conditions frame the promotion as a 30% discount on eSimFLAG orders between 5 May and 30 June 2026, with activation possible within three months of purchase. Spanish telecom media has reported the new summer global price as €2.45 per day for unlimited data across eSimFLAG destinations.

Why is this smarter than another roaming table?

The interesting part is not only the discount. It is the channel.

O2 is using its own customer app as the travel-connectivity storefront. That is exactly where this category is moving. Travellers do not want to compare roaming PDFs while boarding a flight. They want a clean answer before departure, preferably from a brand they already trust.

READ MORE: Telefónica Unveils eSIMFlag, Taking Aim at the Travel eSIM Market

eSimFLAG says it offers unlimited data, instant activation, Movistar support and coverage across more than 170 countries. On paper, that gives O2 a neat customer-retention play. Instead of watching customers leave the operator environment to buy from a travel eSIM specialist, O2 can keep the connectivity moment inside its own app.

This is also why the offer should be watched beyond Spain. Operators used to treat travel eSIMs as a threat to roaming revenue. Now, some are learning to package them as loyalty, not loss.

Where the deal makes sense

For O2 Spain customers travelling outside the usual roaming comfort zone, €2.45 per day is genuinely competitive, especially for people who do not want to calculate gigabytes. A short trip to the US, Japan, Mexico, Morocco or another non-EU destination can quickly become messy if a customer relies only on standard roaming.

It is less compelling for travellers staying inside the EU and EEA, where EU rules extended roam-like-at-home protections until 2032. In those destinations, many Spanish mobile customers already use their domestic allowance with fair-use conditions, so a separate travel eSIM is not always necessary.

It may also be less suitable for people who need a local phone number, voice calls or SMS for banking and reservations. This is primarily a data product. For WhatsApp, maps, ride-hailing, translation apps and social sharing, that is usually enough. For old-school calls, less so.

The bigger eSIM signal

This move lands at a useful moment. GSMA Intelligence says global eSIM smartphone penetration reached around 5% at the end of 2025 and is expected to reach 10% by the end of 2026. Fortune Business Insights projects the wider eSIM technology market to grow from $2.12 billion in 2026 to $7.62 billion by 2034.

Travel is one of the easiest entry points because the pain is obvious. Roaming is expensive, airport Wi-Fi is unreliable, and buying a physical SIM after landing feels increasingly outdated.

READ MORE: The Hidden Economics of Unlimited eSIM Plans

But competition is already sharp. Holafly has trained travellers to understand unlimited eSIMs. Airalo and Nomad eSIM compete strongly on destination-specific pricing. Ubigi brings serious network credibility, especially in cars and connected mobility. Saily leans into app-led simplicity and security. O2’s advantage is different: it owns the customer relationship before the trip starts.

What this really tells us

The O2 eSimFLAG offer is not just a cheap summer deal. It is a sign that mobile operators are starting to respond to the travel eSIM market with the one weapon independent providers do not have: the customer account already sitting on the phone.

The next battleground will not be only price. It will be clarity. Unlimited data sounds great, but users will still want transparent fair-use rules, speed expectations, hotspot terms and network quality by destination. The operator who explains those details best will win more trust than the one shouting “unlimited” the loudest.

For now, O2 Spain has made a smart move. It has taken a product travelers already want and placed it where they are most likely to buy it: inside the app they already use.