Data roaming is the setting that lets your phone connect to networks outside your home country. For a travel eSIM to work, data roaming must be ON. For your home SIM, it should almost always be OFF. This guide explains the difference and walks you through the right configuration.
| Setting | Home SIM | Roamiya eSIM | Why |
|---|
| Data Roaming | OFF | ON | Home SIM roaming triggers per-MB charges from your carrier; eSIM roaming is included in your plan price |
| Mobile Data | OFF (while traveling) | ON | Prevents the phone from routing data through your home carrier |
| Calls/SMS | ON | OFF (default) | Keeps your home number reachable for calls and texts |
The critical mistake is leaving data roaming ON for your home SIM while traveling. Even if you are not actively using data, background app refresh, push notifications, and system updates can trigger roaming charges at rates that run into hundreds of dollars per day depending on your carrier and destination.
Your Roamiya eSIM does not have its own cell towers. It works through roaming agreements with local carriers in each destination -- SoftBank in Japan, Orange in France, AT&T in the United States, and so on. When data roaming is enabled on the eSIM line, your phone can connect to those partner networks and route your data through the plan you already paid for.
The roaming fee is built into the eSIM price. There are no additional charges from Roamiya or from the local carrier.
- Open Settings > Cellular.
- Tap your Primary SIM (home line). Scroll down and confirm Data Roaming is OFF.
- Go back and tap your Roamiya eSIM. Toggle Data Roaming to ON.
- Under Mobile Data, select the Roamiya eSIM as the active data line.
- Turn Allow Cellular Data Switching to OFF.
- Open Settings > Connections > SIM Manager.
- Under Preferred SIMs, set Mobile data to your Roamiya eSIM.
- Turn Auto Data Switching to OFF.
- Go back to Connections > Mobile Networks.
- If your phone shows per-SIM roaming toggles, turn Data Roaming ON for the eSIM only. If it shows a single global toggle, confirm Data Roaming is ON and that Mobile Data is set to the eSIM.
- Open Settings > Network & internet > SIMs.
- Tap your physical SIM (home line). Turn Mobile Data OFF and Roaming OFF.
- Go back and tap your Roamiya eSIM. Turn Mobile Data ON and Roaming ON.
| Travel phase | What to do |
|---|
| Before departure | Configure all settings at home while you have time and WiFi |
| During the flight | Airplane Mode ON (both SIMs silent) |
| After landing | Turn Airplane Mode OFF, wait 1-2 minutes, the eSIM should auto-connect |
If you enable the eSIM settings at home, you will not see signal bars until you reach the destination. That is normal -- the partner networks are not available from your home country. Once you land and turn off Airplane Mode, the phone searches for and connects to a local partner automatically.
If data roaming is ON but the phone shows No Service after landing, the phone may need a network refresh. Toggle Airplane Mode on for ten seconds and back off, then wait a full minute. For more steps, see our
No Service troubleshooting guide.
If data feels slow, you may be on a congested network or hitting a daily data cap on an unlimited plan. See our
slow internet speed guide for diagnosis steps.
