Setting up a travel eSIM takes about two minutes, but doing it in the right order — and over Wi-Fi before you leave Hong Kong — avoids the most common headaches. Here is the whole process for both iPhone and Android, starting with where to buy.
Step 0 — Buy a pack that fits your trip
Buy online before you fly from a global aggregator such as Airalo, Holafly, Nomad or Ubigi, or from a marketplace like trip.com. Pick a data amount that matches your trip (about 1GB/day) and a validity window that covers your dates. You will receive a QR code by email or in the app — that is your eSIM. Keep the confirmation email until the trip is over.
Step 1 — Check your phone supports eSIM
On iPhone, go to Settings → Mobile Data → Add eSIM. On Android, go to Settings → Network & Internet → SIMs → Add eSIM. If the option appears and your phone is carrier-unlocked, you are good to go. Most iPhones from XS onward and recent flagship Android phones support eSIM.
Step 2 — Install over Wi-Fi before you fly
Installing the eSIM needs an internet connection, so do it at home on Wi-Fi — not at the destination airport when you have no data yet. Scan the QR code via the Add eSIM screen above and label the line (e.g. "Japan trip").
Step 3 — On arrival, set it as your data line
- Turn on the travel eSIM line and turn ON data roaming for that line (this is normal for travel eSIMs — it just lets it use the local network).
- Set Mobile Data to the travel eSIM, and keep your Hong Kong SIM as the line for calls and SMS.
- Turn OFF data roaming on your Hong Kong line so it never racks up a roaming bill.
Troubleshooting: no signal at your destination
- Confirm data roaming is ON for the travel eSIM line and it is selected for Mobile Data.
- Toggle Airplane mode off and on to force a re-registration with the local network.
- Manually select the carrier in network settings — the provider app usually lists supported local networks.
- If it still fails, re-download the eSIM from the provider app, or contact support from the app/chat.
Frequently asked questions
Can I keep receiving WhatsApp and bank SMS on my HK number?
Yes. Keep your Hong Kong SIM active as the primary voice/SMS line (with its data roaming OFF). WhatsApp stays tied to your HK number over the travel eSIM’s data, and bank OTP SMS still arrive on the HK line at no roaming cost.
What if the eSIM has no signal when I arrive?
Check that data roaming is ON for the travel eSIM line, that it is selected for Mobile Data, and try toggling Airplane mode. If it still will not connect, manually select the carrier in network settings — the provider’s app usually lists the supported local networks.
Can I buy the eSIM after I have landed?
You can, but you need internet to buy and install it — which usually means finding airport or hotel Wi-Fi first. It is far smoother to buy and install over home Wi-Fi before you fly.