Say you are spending two weeks in Japan and expect to use about 10 GB. Here is how the three classic options play out.
Option 1: carrier roaming
Big carriers price roaming data between $5 and $12 per day or sell "travel passes" that meter both days and gigabytes. Two weeks commonly lands between $70 and $150 — for data you could buy locally for a tenth of that. Roaming's only real advantage: you do nothing, and you keep your number for incoming calls.
Option 2: local SIM at the airport
Tourist SIMs are cheap on paper (usually $15–30), but the real price is time and friction: find the kiosk, queue after a long flight, hand over your passport for registration, swap SIMs and hope your home SIM does not get lost in a backpack. Your home number is offline while the local SIM is in the tray.
Option 3: travel eSIM
A 10 GB / 30-day Japan eSIM costs $18 at Rommy — bought from your sofa, installed in a minute, active the moment you land. Your home SIM stays in place for calls and SMS, and WhatsApp keeps working with your usual number.
The comparison
| Roaming | Airport SIM | Travel eSIM | |
|---|---|---|---|
| Typical 2-week cost (10 GB) | $70–150 | $15–30 | $12–20 |
| Setup time | none | 30–60 min | ~1 min |
| Keep home number active | yes | no | yes |
| Passport / KYC | no | often yes | no |
| Works before landing | yes | no | yes |
For nearly every traveler with an eSIM-capable phone, the travel eSIM is the rational default: local-SIM prices with roaming-level convenience — and at Rommy you can settle the bill in crypto.