Dual-SIM setup for travel: the complete iPhone and Android guide

How dual SIM works

Modern phones run two subscriber identities at once in a mode called Dual SIM Dual Standby. Both lines register on networks and can receive calls, but only one carries data at a time and only one call can be active. For travel this is exactly right: the home SIM listens for calls and OTPs on a foreign partner network while the travel eSIM carries all internet traffic on a local network at local-ish prices.

The phone decides what goes where using defaults you set once. Get the four settings right and nothing else needs touching for the whole trip.

The four settings

The four settings

iPhone step by step

1. Install the travel eSIM (guide) and label it Travel.
2. Settings, Cellular, Default Voice Line: your home SIM.
3. Settings, Cellular, Cellular Data: Travel. On the same screen turn Allow Cellular Data Switching off.
4. Settings, Cellular, tap Travel, Data Roaming on. Tap your home SIM, Data Roaming off.
5. Settings, Messages, Send and Receive: your home number ticked; the travel line has no number to add.
6. Optional: Settings, Cellular, home SIM, Turn Off This Line if you want silence from it, but you lose OTPs.

Status bar: two signal indicators appear. The top one is the voice line, the bottom the data line. iPhone 13 and later can run two eSIMs instead of SIM plus eSIM; the settings are identical. More in eSIM on a dual-SIM iPhone.

Samsung, Pixel and OnePlus

Samsung One UI: Settings, Connections, SIM manager. Under Preferred SIMs set Calls and Text messages to the home SIM and Mobile data to the travel eSIM. Tap the travel eSIM and turn Data roaming on; tap the home SIM and turn it off. One UI 6 and later apply roaming per SIM in this screen; older versions have a single switch under Mobile networks that applies to the data SIM.

Pixel: Settings, Network and internet, SIMs. Tap each SIM: for the travel eSIM turn on Mobile data and Roaming; for the home SIM turn Roaming off. Under Calls and SMS preference choose the home SIM. Pixel 7 and later allow two eSIMs active.

OnePlus: Settings, Mobile network. Set Default for mobile data to the travel eSIM and Default for calls to the home SIM. Data roaming is per SIM inside each SIM's page. Full paths in the Android install guide.

What costs money on the home SIM abroad

Home SIM charges abroad (confirm with your operator)

Before departure, enable international roaming on the home SIM in the operator app. Prepaid SIMs may need a minimum balance to register abroad. Without this the SIM shows No Service abroad and OTPs never arrive.

Edge cases

Single-SIM phone. Older single-slot Android phones cannot hold two lines. Options: a physical travel SIM in place of the home SIM (no OTPs while abroad, so set up app-based authentication before leaving), or carry a second basic phone for the home SIM.

US iPhone with no SIM tray. Move your Indian number to an eSIM through the Jio, Airtel or Vi app a week before travel, then run two eSIMs.

Phone with two physical SIMs already. Most phones allow two active lines in total. Disable one physical SIM in SIM manager for the trip.

WhatsApp. Stays on the number it was verified with and uses whichever line carries data. Nothing to change. Details in WhatsApp on eSIM.

Several travel eSIMs on one phone

Frequent travellers keep profiles for several countries installed. iPhones store eight or more; most Android phones five to seven. Only two lines are active at once, so switch the data line in Cellular or SIM manager when you change country. A regional or Global eSIM removes the switching for multi-country trips. Delete expired profiles when the storage is full; see deleting an eSIM.

Checklist before departure