Open Settings, tap Cellular, pick your line, tap Cellular Data Options and switch Data Roaming on. Do it before you fly, on the line that has a roaming plan from your carrier.
Here’s the full run, plus the simpler route.
What do you need before you turn on roaming on your iPhone?
You need an active line with a roaming plan or pass from your carrier, added before you leave, and an iPhone set up to use that line abroad. Call your carrier or check its app or website before you go, because a plan added in advance is what keeps unexpected high fees off your bill.
Apple Support (About cellular data roaming options for your iPhone and iPad, and Use cellular data on your iPhone or iPad) publishes the steps:
- Before you go, contact your carrier by phone or online to shop international roaming plans to avoid fees and higher rates.
- After arrival, open Settings.
- Tap Cellular or Cellular Data.
- If your device has a single SIM card or eSIM, turn on Cellular Data, then tap Cellular Data Options, and turn on Data Roaming and other settings suggested by your carrier.
- If your device uses Dual SIM or Dual eSIM, turn on Cellular Data, tap the number you want to modify, then tap Cellular Data Options, and turn on Data Roaming and other settings suggested by your carrier.
- To turn data roaming off, go to Cellular Data, then tap Cellular Data Options, and turn off Data Roaming.
Sort the plan first. Then the toggle takes seconds.
Which line do you switch Data Roaming on with two SIMs?
Switch it on for the line you plan to use for data abroad, because each line has its own Data Roaming switch. Tap that line’s name under Cellular, then Cellular Data Options, then turn Data Roaming on.
Apple Support (About cellular data roaming options for your iPhone and iPad) lays out the per-line steps:
- Open Settings.
- Tap Cellular or Cellular Data.
- Turn on Cellular Data.
- Tap the number you want to modify.
- Tap Cellular Data Options.
- Turn on Data Roaming and other settings suggested by your carrier.
The same logic holds for a Maya eSIM sitting beside your regular SIM. Keep your own SIM as Primary for Voice/SMS and iMessage, and give the Maya Mobile eSIM the job of carrying mobile data. Turn On This Line and Data Roaming must both be ON for the eSIM plan, and on landing you switch on the Maya eSIM and select it for Cellular Data.
Two lines, two switches. Flip the right one and you’re done.
What do you do if your iPhone shows No Service abroad?
Turn Airplane Mode on for 30 seconds, then off, so the iPhone searches for a local partner network. Then check that Date & Time is set to Set Automatically under Settings, General, Date & Time.
Apple Support (About cellular data roaming options for your iPhone and iPad) publishes the full run:
- If the date and time are wrong after you arrive, open the Settings app and tap General, and then tap Date & Time. Make sure that Set Automatically is turned on.
- Turn on Airplane Mode for about 30 seconds. Then turn it off again and let your iPhone automatically select the best network.
- If you see No Service or SOS only in the status bar of your iPhone, open the Settings app and tap Cellular or Cellular Data. Then:
- If your device has a single SIM card or eSIM, turn on Cellular Data, then tap Cellular Data Options, and make sure Data Roaming is on.
- If your device uses Dual SIM or Dual eSIM, turn on Cellular Data, tap the number you want to modify, then tap Cellular Data Options, and make sure Data Roaming is on.
- If you still need help, try a different SIM card or contact your carrier for more information.
- If you use an iPhone with an eSIM, learn more about your travel options for eSIM.
Still stuck after step 4? Your carrier is the next call.
When should you skip carrier roaming and use a travel eSIM?
Maya sells one Global eSIM by trip length: 3 days is $9.99, 7 days is $19.99, 14 days is $27.99 and 30 days is $49.99.
Roaming has its own pain on the other side of the counter. A 2-star Trustpilot review of Saily by Michael F., from September 23, 2025, reads: “Easy to setup, although haven’t used it yet. Added 2nd day: At arrival, Lisbon airport free wifi sign-in was showing a browser 404 error page, while my wife’s phone signed in fine. Changing to Saily eSim1 was easy enough, turning roaming on, but getting decent data rate, even after 2 reboots, barely any signal, Saily chat was on and off line, Speedtest was showing no connection. Was on with 4 different agents – frustrating – not enough bandwidth to send screenshots, so a lot of typing. Through spoty internet, has to update to truphone.com entry, NOS 1Global API and one other custom setting on my new Zfold7. Well over 2 hours, 6:30 am flight arrival till close to 10:30 by the time I was able to get setup, so I could a decent internet access to access Google Maps and train info, to see where I needed to go for my hotel. Never had this much trouble ever! Once I was able to get it working making several custom setting changes from live agent assistant, then it was good, meanwhile my phone was half dead using it for so long trying to get a decent internet signal. My signal bars were full, just settings were all wrong. I don’t understand why I had to go through all of this, then have to make several custom modifications to network setup on the new eSim from Saily… Why would they not be pre-configured or at least have these settings in some instructions as part of the eSim installation or part of the instructions after purchasing the 10Gig 30 day plan, the system knew it was for Portugal, there was no specific instructions on required custom network settings and took several hours to get it working…. I read reviews with a high rating. Can’t imagine having to go through this every time I travel somewhere, so I don’t know how I can use the same service again, knowing I may have to go through this again, meanwhile my wife had to wait with me for several hours. I knew about the tips to not get charged extra when arriving in another Country, installing the Saily eSim, but the custom settings for API and service types was not know until after I was at the mercy of a severely poor data connection with full bar signal and not able to use the Lisbon Portugal free airport wifi. Now that it is up, it seems fine for the 2nd day using it. The reason for 2 stars is having to spend hours trying to setup with 4 different live chat agents, which were fine, but had repeats of similar info to resolve my initial connection issues, until it finally worked… Sitting on stone ledge for over an hour and over an hour outside the airport trying to get a internet signal – was a wonder I was able to even chat with Saily tech agents in the first place.”
Which travel eSIM should you put on your iPhone for this trip?
The table lists what each travel eSIM company publishes about how it prices and what its unlimited plans allow, so you can match one to your trip length and iPhone. Maya’s row is from maya.net; each rival’s cells are its own published words, or a short summary of what it states.
| Travel eSIM | How plans are sold | Unlimited plan allowance, as published | Calls, texts and phone number, as published |
|---|---|---|---|
| Maya Mobile | One Global eSIM for 165+ countries, unlimited data at a flat price by trip length: USD 9.99 for 3 days, USD 19.99 for 7 days, USD 27.99 for 14 days, USD 49.99 for 30 days | A daily high-speed data allowance (the Daily Quota) at up to 4G LTE or 5G where local networks offer it, reset every 24 hours; unlimited data at standard speed once the Daily Quota is used | Data only, with no local number; your own SIM stays in the phone for your calls and texts |
| Airalo | Per country, per region, or one global plan; priced in USD | Our unlimited data packages don’t have a fixed total data cap. However, to keep the network running fairly for everyone, when you use more than 3GB in a day, we’ll slow down (or “throttle”) your internet speed to 1 Mbps for the rest of that day. Your full high-speed connection will automatically be restored when your daily allowance next resets. Your daily allowance resets every 24 hours, counted from the time you activated your eSIM. | We offer flexible data packages — some have calls and texts. |
| Holafly | Per country, per region (Europe, Latin America, Cruise plans), and monthly global plans: Light, 25GB of data, $ 49.90USD/month; Unlimited, $ 64.90USD/month; Ultra, $ 90.95USD/month | Unlimited data plans are subject to a fair use policy, which may temporarily reduce speed in cases of unusually high usage to maintain network quality for all users. | Unlimited Plans purchased on November 4, 2025, or later include a phone number for US, UK, or Canada. Please note that this service supports inbound SMS only and VOIP-based calling (traditional incoming cellular calls are not supported) |
| Saily | Per country and per region, plus one global plan; by the gigabyte, unlimited, or both | The Unlimited plan gives you 5 GB per day at full 4G/5G speed, then keeps you online at 1 Mbps for the rest of the day — fast enough for navigation, messaging, and standard browsing. | Yes, you can keep your own number while using a Saily eSIM plan. If you want to make calls and send SMS messages abroad without worrying about extra carrier fees, you can add a US phone number to your Saily eSIM plan. |
| Nomad | Per country, per region and global plans; by the gigabyte and unlimited | Once the daily allowance of 2 GB is used, data speeds are reduced (throttled) for the rest of the day. Depending on the specific plan, this reduced speed is approximately 1 Mbps or 2 Mbps. | Some of Nomad’s eSIMs include a local phone number. Check the plan details for more information of what your plan includes. |
How Maya lets you install once and switch on data for every trip
A roaming toggle only works if a plan sits behind it, line by line, trip by trip. Maya turns that into one switch: install the eSIM once, pick a flat-price plan for the trip length, and buy the next trip’s plan from the app.
Choose from 3-day, 7-day, 14-day or 30-day plans, each giving unlimited data in 165+ countries. Maya is installed once and stays on the phone permanently. For each trip you only buy a new plan, with no reinstalling.
Peter S. gave Maya five stars on Trustpilot in April 2026: “I am on my sailboat traveling from Florida to Antigua. I have been using a Maya Caribbean eSIM during this trip and have had seamless data throughout. Maya remind you when your eSIM Is running low so that you can top up. If you have a problem, Maya customer service is contactable by email – they are polite, responsive, helpful and efficient. It is great value for money, it works and I am happy.”
FAQ
What does Data Roaming do on an iPhone?
Data Roaming lets the iPhone use mobile data on a partner network when you are outside your carrier’s coverage. Apple Support says it “permits internet access over a cellular data network in regions that are not covered by your carrier’s network” (Apple Support, About cellular data roaming options for your iPhone and iPad, 2026). Apple also says: “When you’re traveling internationally, you can turn off data roaming to avoid roaming charges. If you have an international data plan, you may need to keep Data Roaming on.” (Apple Support, Use cellular data on your iPhone or iPad, 2026). With more than one active line, enable it for the exact line you plan to use for travel data.
What decides whether data roaming on an iPhone costs extra abroad?
Your carrier’s roaming plan or pass sets what you pay abroad, so check before you leave. T-Mobile, for one, publishes a pass: “1 Day (2GB) International Data Pass: 2GB of high-speed data at up to LTE speeds and unlimited calling in 215+ countries and destinations, to be used up to 24 hours, for $10.” (T-Mobile, International Pass: Add Unlimited Calling & International Data). Call or check your carrier’s app or website to add a pass and avoid unexpected high fees.
What setting does a Maya eSIM need on your iPhone to get data abroad?
Data Roaming must be ON for the Maya eSIM, and Turn On This Line must be on too. On landing, you switch on the Maya eSIM and select it for Cellular Data. Choose Primary for Voice/SMS and iMessage, and use the Maya Mobile eSIM for mobile data only. To set the Default Voice Line, open Settings > Cellular (may be called Mobile or Mobile Service), tap Default Voice Line, and select Primary, the line with your phone number.
Which iPhones work with the Maya Global eSIM?
The compatible list runs from the iPhone XR/XS series through the iPhone 17 series, including iPhone Air, SE 2 (2020) and SE 3 (2022). Check the complete device list at maya.net/esim-compatible-devices before you buy.
How long does a Maya Global eSIM plan last once you buy it?
Plans last 3, 7, 14 or 30 days, all with unlimited data across 165+ countries. The 3-day plan costs $9.99, the 7-day plan $19.99 and the 30-day plan $49.99. The 3-day plan suits weekend trips and short getaways.
How do you keep your usual number while using a travel eSIM on your iPhone?
After activating a Maya Mobile eSIM, you can keep using your existing phone number to send and receive calls and text messages (SMS). Set the Primary line as the Default Voice Line, and use the secondary line, the eSIM plan, for data only. If your carrier supports Wi-Fi Calling and it is enabled, the phone connects to your home carrier’s network over the internet using the eSIM data connection (VoIP), allowing calls and texts with your regular number.
When should you set up roaming or an eSIM before a trip?
Set up before you leave. Call or check your carrier’s app or website before you go to add a roaming pass. For a Maya eSIM, installing requires a working Wi-Fi or cellular internet connection, because the connection is needed to verify and activate it. The plan clock starts when you enable the Maya eSIM in phone settings, and if you installed before arriving, set it as the primary Cellular/Mobile Data plan on arrival.
What happens when your Maya plan’s days run out?
The plan ends with no further charge, because Auto Top-Up is opt-in only and off by default. Turn Auto Top-Up on only if you want the next plan bought for you. Otherwise, buy another plan from the app when you need more days.
Maya gives your iPhone one eSIM with unlimited data across 165+ countries, installed once, with a flat price by trip length.
