How to turn on Wi-Fi Calling: set up calls over Wi-Fi on iPhone and Android

How do you turn on Wi-Fi Calling, and how long does it take?

You turn on Wi-Fi Calling in your phone’s settings: on iPhone it sits under Cellular > Wi-Fi Calling, and on most Android phones it sits in the Connections or SIM menu. It only works once the carrier behind that number has enabled it for you, and if both the phone and the carrier support it, the whole job takes a few minutes.

Wi-Fi Calling (technically VoWiFi) lets you make and receive calls on your normal mobile number while the voice travels over a Wi-Fi network instead of a cell tower. The phone builds an encrypted IPsec tunnel across the internet to a carrier gateway called the ePDG, then registers with the same IMS core that VoLTE uses. That is why turning it on always has two sides: the phone side (the switch in the menu) and the carrier side (your number’s entitlement plus the carrier settings loaded on the phone). If you want the background first, the explainer below covers how it works.

What is Wi-Fi Calling and how does it work?

What do you need to check before turning on Wi-Fi Calling?

Most people who cannot find the menu, or who switch it on and see nothing happen, are stuck on one of the basic conditions below. Checking them first saves a lot of time. True-dtac’s and Samsung’s own guides list much the same conditions: an active SIM, a supported phone and up-to-date software.

• The SIM or eSIM for your Thai number must be active, not suspended, and able to make and receive normal calls. True-dtac lists this explicitly on its setup page.
• The phone must support Wi-Fi Calling with that carrier. Apple says iPhone 5c or later works on a supported carrier; Android depends on the model and firmware. AIS points customers to ais.th/4g/vowifi to check their model.
• Update the operating system and the carrier settings. On iPhone, open Settings > General > About; if a carrier settings update is waiting, a prompt appears asking you to update.
• You need Wi-Fi with a working internet connection that is past any login page (captive portal) and does not block UDP ports 500 and 4500, which the phone uses to build the IPsec tunnel to the ePDG.
• Imported phones, or phones running another country’s firmware, may never show the Wi-Fi Calling menu, because the Thai carrier’s configuration is not loaded in that firmware.

How do you turn on Wi-Fi Calling on iPhone?

The steps below follow Apple’s support article, which still uses the Cellular > Wi-Fi Calling path (called Mobile Data or Mobile Service in some countries) and applies to iOS 18 and iOS 26. If you do not see it there, open Settings and type Wi-Fi Calling into the search field at the top.

1. 1Open Settings and tap CellularIf the phone has two lines (a physical SIM plus an eSIM, or two eSIMs), scroll down and tap the Thai number you want to use with Wi-Fi Calling first. The switch sits inside that line’s page.
2. 2Tap Wi-Fi CallingIf this row is missing entirely, the carrier or the carrier settings on the phone have not enabled it for this number yet. Jump to the carrier section below.
3. 3Turn on Wi-Fi Calling on This iPhone and tap EnableApple notes that some carriers ask you to enter or confirm an address for emergency services. Use the real address where you spend most of your time, because the carrier may use it to route an emergency call placed over Wi-Fi.
4. 4Connect to Wi-Fi and check the statusPer Apple, once Wi-Fi Calling is available you will see Wi-Fi in the status bar when you open Control Center, next to the carrier name. AIS customers see an AIS WiFi Call label.

Dual-SIM iPhones have one more wrinkle. Apple explains that if the carrier of your other number supports Wi-Fi Calling, you can answer incoming calls on that number while you are on a call on the first one. If the line you are talking on is not your designated cellular-data line, you need Allow Cellular Data Switching turned on, otherwise cellular data stops during the call. The iPhone-only guide goes deeper.

Full guide: Wi-Fi Calling on iPhone

How do you turn on Wi-Fi Calling on a Samsung Galaxy?

Samsung offers three ways in, and all three flip the same switch, so use whichever you find first. The steps match One UI 6, 7 and 8 as they ship today, though labels can shift slightly by model and carrier.

1. Through Settings: Settings > Connections > Wi-Fi Calling, then turn the switch on. With two SIMs, turn it on for the Thai number you want (True-dtac’s guide confirms this works for a physical SIM or an eSIM).
2. Through the Phone app: open Phone > tap the three dots (More options) > Settings > turn on Wi-Fi Calling.
3. Through Quick settings: swipe down from the top (on One UI 7 and later, from the top-right) and tap the Wi-Fi Calling tile. If the tile is not there, use Edit to add it.
4. Inside the Wi-Fi Calling page, set the calling preference to Wi-Fi preferred, which is what True-dtac recommends. If a pop-up asks for emergency contact details, fill them in and tap Save.

Samsung’s help page stresses that Wi-Fi Calling is not the same as an internet calling app like LINE: it uses the talk time and minutes of your carrier’s plan, so it is not automatically free, and the feature may not be offered in every country or on every carrier.

Full guide: Wi-Fi Calling on Samsung Galaxy

How do you turn on Wi-Fi Calling on a Pixel and other Android phones?

For Google Pixel, Google’s help page gives the path Settings > Network & internet > SIMs > your carrier SIM > Wi-Fi calling, then turn it on. Google adds that you need Android 6.0 or later, and that if the option does not appear, your carrier does not support the feature on that SIM. During a Wi-Fi call the notification area shows Internet call or Wi-Fi calling.

Other Android brands such as Xiaomi (HyperOS), OPPO (ColorOS), realme and vivo mostly put the switch in the SIM menu, for example SIM cards & mobile networks or Dual SIM & Cellular > your SIM > Wi-Fi calling. The labels change often between models and versions, so the most reliable method is to type Wi-Fi calling or VoWiFi into the Settings search bar. After you turn it on, set the preference to Wi-Fi preferred if the phone offers a choice.

• Wi-Fi preferred: when usable Wi-Fi is available, the phone calls over Wi-Fi first. Good for high-rise flats or rooms with weak signal, and the setting you want when you are abroad.
• Cellular (mobile network) preferred: the phone sticks with the cell network and only uses Wi-Fi when there is no signal. Fine for people in Thailand who already have good coverage.
• Some models also offer Wi-Fi only, or a separate preference while roaming. If you see one, set it to use Wi-Fi while abroad; the name and location depend on the model and carrier.

Full guide: Wi-Fi Calling on Android

Do you need to register Wi-Fi Calling with AIS, True, dtac or NT?

It depends on the carrier, because Wi-Fi Calling is a service the carrier has to enable for your number; the switch on the phone is only half of it. Apple’s carrier list shows AIS, dtac and True in Thailand all supporting Wi-Fi Calling and VoLTE on iPhone. The carrier-side steps are summarised below.

On cost, every carrier bills outgoing Wi-Fi calls against your plan like a normal call, so they are not automatically free, and prepaid and postpaid rules can differ. AIS’s service page sits in its postpaid section, and after the True-dtac merger there is no page that clearly states prepaid eligibility. If your number is prepaid, ask the carrier’s call centre before you travel. Each carrier has its own guide in this series.

• AIS: see the Wi-Fi Calling on AIS guide for steps and caveats.
• True: see the Wi-Fi Calling on True guide for post-merger conditions.
• dtac: see the Wi-Fi Calling on dtac guide, especially the rule about turning it on in Thailand.

How can you tell Wi-Fi Calling is actually working?

A switch that is on does not mean the phone has registered. It first has to reach the ePDG and register with IMS, and you can see when that has happened from the label on screen. The surest test is to take cellular away and see whether you can still call. Do this at home before you travel.

1. 1Turn on Airplane ModeThis cuts the cellular radio so the phone must rely on Wi-Fi alone. Both AIS and True-dtac use this step in their own guides.
2. 2Turn Wi-Fi back on and join a networkWi-Fi can be turned on while Airplane Mode stays on. On hotel or café Wi-Fi, open a browser and finish any login page first.
3. 3Wait up to a couple of minutes and look for the labeliPhone: open Control Center and look for the carrier name followed by Wi-Fi, or AIS WiFi Call. Samsung: a phone-with-Wi-Fi icon in the status bar (varies by model). Pixel: Wi-Fi calling under the carrier name. If nothing appears, registration has not succeeded.
4. 4Make a test call and get someone to call youCall a friend or a number you know, then ask them to call you back. If both outgoing and incoming work in Airplane Mode, you are ready to travel. Never use an emergency number as your test.

On Android there is one more check that technicians use: type *#*#4636#*#* in the Phone app to open the Phone information screen, then tap the three-dot menu > IMS Service Status to see whether Wi-Fi Calling shows as registered. This code is not from Google’s official help and some brands disable it, so treat it as a diagnostic aid rather than the main method.

Going abroad: how should you set up Wi-Fi Calling so it works?

The rule is to switch it on and test it while you are still in Thailand. True-dtac says plainly that you must turn it on in Thailand and not turn it off. AIS advises Airplane Mode and waiting for the AIS WiFi Call label before every call abroad. If you dial while the phone is attached to a local network overseas, the call may be charged as roaming instead.

1. Before you leave: turn on Wi-Fi Calling for your Thai number, set Wi-Fi preferred, and run the Airplane Mode test from the previous section.
2. If you will use a travel eSIM: install it in advance, keep your Thai number as the voice line, set the travel eSIM as the cellular-data line, and turn off data roaming on the Thai line.
3. At your destination: when you need to call or take calls on the Thai number, join working Wi-Fi and wait for the Wi-Fi Calling label before you dial.
4. If hotel Wi-Fi fails: True-dtac warns that some free Wi-Fi abroad does not support the service, so try another network or a hotspot from another device that has data.

esimonline eSIMs are data-only with no phone number, so they have no Wi-Fi Calling of their own. All the Wi-Fi Calling in this article belongs to your existing Thai number (AIS, True, dtac, NT). A travel eSIM gives the phone mobile data and can share it as a hotspot. Some users on Thai forums describe the Thai line’s Wi-Fi Calling riding on the other SIM’s mobile data inside the same phone (sometimes called backup calling), but no Thai carrier confirms this on an official page, so do not build your plan around it. The route carriers document is Wi-Fi.

Using Wi-Fi Calling abroad: what to know

Can’t turn on Wi-Fi Calling, or the menu is missing: what should you do?

If the menu is missing entirely, the cause is almost always on the carrier or firmware side, not a setting on the phone. If the menu is there but the label never appears, the Wi-Fi network or the registration is usually to blame. Work through this order.

1. Update the software and carrier settings, then restart. Google notes that the phone turns Wi-Fi Calling off by itself if it detects a problem, and a restart may help.
2. On AIS with Android, dial *399*1# again; on NT, dial *834# and choose to enable Wi-Fi Calling.
3. Switch to a different Wi-Fi network or another phone’s hotspot to rule out a router that blocks UDP 500/4500.
4. On an imported phone or foreign firmware, the menu may not exist at all because the firmware lacks the Thai carrier’s configuration. No setting fixes that.
5. Still stuck? Call your carrier’s call centre and ask them to check that VoWiFi is provisioned on your number.

Wi-Fi Calling not showing? Fixes for a missing menu