Dual SIM + eSIM: Data and Call Settings

TL;DR

• Data on eSIM and data roaming OFF on home USIM → avoid high roaming abroad.
• Calls/SMS on home USIM (default voice) → receive calls and SMS on your home number.
• On both iPhone and Galaxy, set cellular data to use the eSIM line.

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Why separate these settings?

With dual SIM (USIM + eSIM):

• Data on eSIM → overseas data is billed only to the eSIM plan (cheap).
• Data on home USIM → roaming charges may apply (expensive).
• Calls/SMS on home USIM → use your home number for calls and SMS (data/Wi‑Fi can still use eSIM).

So a common setup is: data = eSIM, default voice = home USIM.

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iPhone settings

1. Settings → Cellular (or Mobile Data)
2. Cellular data → set data to eSIM
3. Default voice to home USIM (to receive calls/SMS on home number)
4. Data roaming OFF for home USIM (avoid high roaming)

Result:

• Internet/app data → eSIM
• Calls/SMS → home USIM number

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Android (Galaxy etc.) settings

1. Settings → Connections → SIM manager
2. Mobile data → set data SIM to eSIM
3. Voice / SMS → set default to home USIM
4. Data roaming OFF for home USIM

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Checklist

• Home USIM data roaming OFF
  If home USIM uses data abroad, roaming charges apply. See How to turn off data roaming on home SIM.
• Default voice = home USIM
  To receive calls/SMS on your home number, set default voice to home USIM.
• Wi‑Fi
  When on Wi‑Fi, data uses Wi‑Fi first; turn Wi‑Fi off to verify eSIM data is used.

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Summary

Item	Recommended
Data	eSIM
Default voice/SMS	Home USIM
Home USIM data roaming	OFF

This is the most common dual SIM + eSIM setup for travel.