Recommended dual-SIM setup: home line + travel eSIM

Most travellers want their home phone number to keep receiving voice calls, SMS codes (banking, 2FA, Uber confirmations) while the travel eSIM handles all data. Here's the cleanest setup.

iPhone

• Settings → Cellular
• Default Voice Line: Primary / home line
• Cellular Data: Travel eSIM
• Cellular Data Switching: OFF (turning this ON would let calls use your home line via data — fine if your home line has free roaming, expensive if not)
• iMessage & FaceTime: leave both ticked for your home line so iMessages keep coming through over the travel data.

Android (varies by brand — Pixel example)

• Settings → SIMs
• Tap home line → Calls: Yes, SMS: Yes, Mobile data: No
• Tap travel eSIM → Calls: No, SMS: No, Mobile data: Yes
• Settings → SIMs → "Roaming" for the travel eSIM: ON (it's literally roaming)

What still works

• WhatsApp, Telegram, iMessage, Signal — all bound to your home phone number and they route over data, so they work as normal on the travel eSIM's data.
• Banking apps that require an SMS code — your home SIM receives the SMS, no extra charge from the bank's side (your home carrier may charge for incoming SMS while abroad — check before).
• Apple Pay, Google Pay — the wallet doesn't care which SIM is active.

What to watch out for

• If you receive a voice call on your home line, the phone has to switch the radio to your home carrier briefly to ring. On 4G/5G phones this is seamless. On 3G-fallback phones it can blip your data for 20-30 seconds.
• Some Android phones drop one SIM into 3G when the other is on 4G. If your travel eSIM is suddenly slow, check "Preferred network type" → set the travel eSIM to "5G/4G".