What is data roaming? Should it be on abroad, and does it cost anything?
Data roaming is the switch that lets a SIM use mobile data on a network that is not its own. Abroad it decides two things at once: whether your travel eSIM works at all, and whether your home SIM runs up roaming charges. The rule is short: on for the travel eSIM, off for the home SIM.
What data roaming is
At home your SIM uses its own carrier’s network. Abroad it connects through a local carrier, which is roaming; the data roaming switch says whether that SIM may use mobile data while roaming. Calls and texts are not affected by it.
Abroad: which on, which off
- Travel eSIM or travel SIM: turn data roaming on. A travel plan reaches the local network by roaming, so with the switch off it shows signal but gets no data.
- Home SIM: turn data roaming off. Otherwise the phone may use it for data, at your carrier’s roaming prices.
- Set mobile data to use the travel eSIM or SIM.
- With data roaming off, the home SIM still receives calls and text codes, provided international roaming is on for it.
Where the switch is
iPhone
- Settings → Mobile Data (Cellular).
- Tap the line (SIM) to change.
- Turn Data Roaming on or off.
Android
- Settings → Network & internet (or Mobile network) → SIMs.
- Tap the SIM.
- Turn Roaming on or off. Names differ a little between brands.
Does it cost anything?
- The switch itself costs nothing.
- On a travel eSIM or SIM, the data is already paid for in the plan.
- On your home SIM, data used while roaming is charged at your carrier’s roaming prices, often by the day.
Data roaming and international roaming
International roaming is a service on your carrier’s side: whether your number works abroad at all, for calls, texts and data. Data roaming is a switch on your phone that only governs data. To get text codes abroad you need international roaming on for the home SIM; to avoid data charges, keep its data roaming off. The other usual mistakes
Turning international roaming on and off with China Mobile, Unicom and Telecom, and what it costs
Questions
What does data roaming mean?
It lets a SIM use mobile data on a network that is not its own carrier’s, as it must abroad. It only affects data, not calls or texts.
Should data roaming be on or off abroad?
On for the travel eSIM or SIM, or it gets no data. Off for your home SIM, or it may run up roaming charges.
Does data roaming cost money?
The switch costs nothing. Travel plans include their data; your home SIM’s roaming data is charged by your carrier.
Where do I turn on data roaming?
iPhone: Settings → Mobile Data, tap the SIM, Data Roaming. Android: Settings → Network & internet → SIMs, tap the SIM, Roaming.
Is data roaming the same as international roaming?
No. International roaming is your carrier’s service that lets your number work abroad; data roaming is the phone’s switch for data only.
What should I turn off on my phone abroad?
Data roaming on your home SIM, and photo backup and app updates over mobile data. Keep the home SIM itself on, so text codes still arrive.