Wi-Fi Calling on iPhone: where to turn it on and how to check it works

Where is Wi-Fi Calling on iPhone?

Wi-Fi Calling on iPhone lives at Settings > Cellular > Wi-Fi Calling, where you switch on “Wi-Fi Calling on This iPhone”. In Thai-language iOS the feature is labelled “การโทรผ่าน Wi-Fi” rather than “WiFi Calling”, which is why people with a Thai interface often cannot find it by searching the English name.

1. 1Open Settings and tap CellularIn some regions the menu is called Mobile Data instead of Cellular; it sits in the same place, near Wi-Fi and Bluetooth at the top of Settings.
2. 2On dual SIM, tap the line firstUnder SIMs you will see each line by its label, such as Primary or Travel. Tap the Thai number you want to use over Wi-Fi. With a single SIM, skip this step.
3. 3Tap Wi-Fi Calling and turn it onTurn on “Wi-Fi Calling on This iPhone”. A confirmation screen appears.
4. 4Tap Enable and confirm an address if askedSome carriers ask you to enter or confirm an address for emergency services at this step. Use the real address where you normally use the phone.
5. 5Join Wi-Fi and check Control CenterGive the phone a moment to register, then swipe down from the top-right corner. If the carrier name is followed by “Wi-Fi”, it is ready.

Several Thai articles still point to Settings > Phone > Wi-Fi Calling, which is where the switch sat in older iOS releases, and True-dtac’s own setup page words it as Settings > Connecting > Wi-Fi Calling. If you cannot find it that way, go to Cellular as Apple’s guide shows. Small differences in menu names come from the language and iOS version; they do not mean your phone lacks the feature.

What do you need before Wi-Fi Calling works on iPhone?

The switch on the phone is only half of it; the other half sits with the carrier. Wi-Fi Calling is the 3GPP VoWiFi standard: the phone builds an IPsec tunnel over Wi-Fi to a carrier gateway called the ePDG and registers with the carrier’s IMS core. If the carrier has not enabled the service for your number, or the phone lacks carrier settings that support it, the menu will not appear or will not work once switched on.

• A supporting carrier: Apple’s Asia-Pacific carrier features page lists AIS, dtac and True in Thailand with both VoLTE and Wi-Fi Calling on iPhone.
• The service enabled on your number: some carriers switch it on automatically, others need you to register. AIS’s iOS help page points to registering through the AIS website. Whether prepaid lines qualify is something to confirm with the carrier.
• Current carrier settings: Apple says carrier settings updates can add features such as Wi-Fi Calling. See the version at Settings > General > About, next to Carrier.
• Up-to-date iOS: Apple lists updating the software as one of the first checks when it will not turn on.
• A Wi-Fi network that lets it through: the IPsec tunnel uses UDP ports 500 and 4500, which some office or hotel networks block. Apple itself notes that not every Wi-Fi network works with Wi-Fi Calling.

Start with the basics: what Wi-Fi Calling is and how it works

Which line should have Wi-Fi Calling on a dual-SIM or eSIM iPhone?

Turn it on for the line that has a phone number and a supporting carrier. For most Thai users that is the AIS, True or dtac number they use for calls and bank OTPs. On the Cellular screen each line has its own settings page, so switching it on for one line does not switch it on for the other.

A data-only travel eSIM has no phone number, so there is nothing for it to call from over Wi-Fi. Some will not show a Wi-Fi Calling entry at all, which is normal and needs no fixing.

Apple’s Dual SIM guide has a rule most people miss: a line must have Wi-Fi Calling turned on to receive calls while the other line is on a call. If no Wi-Fi is available at that moment, iPhone uses the cellular data of the line that is on the call to receive the other line’s call, and charges may apply. That busy line must be allowed to use data, either as the default data line or with Allow Cellular Data Switching turned on. If you do not turn on Wi-Fi Calling for a line, calls to it while the other line is busy go straight to voicemail, with no missed-call notification.

Set up dual SIM on iPhone step by step

How do you check that Wi-Fi Calling on iPhone is really working?

The clearest sign is the word “Wi-Fi” after the carrier name in the status bar. Apple states that when Wi-Fi Calling is available, “Wi-Fi” is displayed after your carrier name and all your calls go through Wi-Fi. On an AIS line it reads “AIS Wi-Fi”; on True or dtac it is that carrier’s name followed by Wi-Fi.

1. iPhones with Face ID or the Dynamic Island: the Home Screen has no room for the carrier name, so swipe down from the top-right corner to open Control Center; the carrier name is at the top left.
2. iPhones with a Home button, such as iPhone SE: the carrier name already shows at the top left of the status bar.
3. Dual-SIM iPhones: Control Center shows both carriers on two lines; look for Wi-Fi after the Thai line’s name.
4. Do a real test: turn on Airplane Mode, turn Wi-Fi back on, wait for “Wi-Fi” to appear next to the carrier name, then call someone you know. If the call connects with the cellular radio off, it really went over Wi-Fi.

The Airplane Mode test is also what AIS and True-dtac recommend for use abroad, because if the phone is still attached to a foreign mobile network the call may go out as normal roaming instead. At home in Thailand with good signal, iPhone may pick Wi-Fi or cellular depending on conditions. If Wi-Fi drops mid-call, Apple says the call moves to the carrier’s cellular network over VoLTE automatically, provided VoLTE is available and turned on.

What is the emergency-address screen, and do you have to fill it in?

When you tap Enable, some carriers ask you to enter or confirm an address for emergency services. The reason is that a call over Wi-Fi has no cell tower to help place you. Apple notes that some carriers may use the address you registered when signing up for Wi-Fi Calling as your location, so enter a real address and update it when you move. If your carrier does not show this screen, there is nothing else to do.

• When cellular service is available, iPhone routes emergency calls over cellular.
• If there is no cellular service and Wi-Fi Calling is on, emergency calls may go over Wi-Fi, and the device’s location may be used to help responders whether or not Location Services is on.
• Apple warns that while connected to Wi-Fi Calling, iPhone may not receive emergency alerts.
• Abroad, call the local emergency number over a mobile network where you can; turn Airplane Mode off first if needed.

Can you take your iPhone calls on iPad, Mac or Apple Watch?

Yes, but there are two different things. The first is Calls on Other Devices, where your iPhone relays calls to an iPad or Mac that is on the same Wi-Fi network and signed in to the same Apple Account. The second is Wi-Fi Calling on iCloud-connected devices, which lets the iPad or Mac call even when the iPhone is not nearby, but the carrier has to support that feature separately.

On Apple’s carrier features page (checked 27 September 2026), some Asian carriers list “Wi-Fi Calling on supported iCloud-connected devices”, but AIS, dtac and True do not; they list plain Wi-Fi Calling only. So for a Thai number, expect the first kind: your iPad or Mac rings when it is on the same Wi-Fi as your iPhone.

1. 1On iPhone: turn on Calls on Other DevicesGo to Settings > Apps > Phone > Calls on Other Devices (or from that line’s Cellular screen), turn on Allow Calls on Other Devices, then switch on each device under Allow Calls On.
2. 2On iPad: turn on Calls from iPhoneGo to Settings > Apps > FaceTime and turn on Calls from iPhone. Make sure FaceTime uses the same Apple Account as the iPhone.
3. 3On Mac: turn it on in FaceTimeOpen FaceTime, choose FaceTime > Settings, and turn on Calls from iPhone. The Mac must be on the same network as the iPhone, over Wi-Fi or Ethernet.
4. 4Apple Watch: turned on automaticallyApple says Wi-Fi Calling is enabled automatically for Apple Watch when you turn on Allow Calls on Other Devices on the iPhone.

If a device does not appear in the list, check that the iPhone has both Wi-Fi Calling and Allow Calls on Other Devices turned on, and that every device uses the same Apple Account for FaceTime and iCloud. With dual SIM, calls you start on a Mac or iPad go out on the Default Voice Line.

What extra setup does Wi-Fi Calling on iPhone need when you travel?

Turn Wi-Fi Calling on and test it while you are still in Thailand. True-dtac’s setup page says plainly that the feature must be switched on in Thailand and left on, or it may not be possible to enable it abroad. At your destination, turn on Airplane Mode, turn Wi-Fi back on, join the hotel or café network, and wait for the carrier name followed by Wi-Fi before you call, as both AIS and True-dtac advise.

Travel-eSIM users often ask whether, with no Wi-Fi around, the Thai line can call over the travel eSIM’s data. Apple’s guide confirms only one case: while the other line is on a call, iPhone can use that line’s data to receive an incoming call on the second line. Apple does not say the Thai line will register Wi-Fi Calling over the other SIM’s data at all times. Thai users in forum threads report both success and failure depending on carrier and country, so do not plan a trip around it. Test it yourself first and treat a real Wi-Fi network as the dependable route.

• Charges: Wi-Fi Calling from abroad is billed under your carrier’s package terms and is not always free; check your carrier’s official page before you go.
• Some Wi-Fi will not work: True-dtac warns that free Wi-Fi in some countries does not support it; try another network or a hotspot from another device.
• Wi-Fi with a login page: finish the captive-portal login first, or the tunnel to your carrier cannot connect.
• OTPs and SMS: once Wi-Fi Calling is registered, the Thai line can often receive SMS too, but this depends on the carrier, so test before you travel.

Full guide to using Wi-Fi Calling abroad

Wi-Fi Calling on iPhone is missing or not working: how do you fix it?

Separate the symptoms first. If the menu is missing entirely, the cause is usually the carrier or the carrier settings. If the menu is there and switched on but “Wi-Fi” never appears next to the carrier name, the cause is usually the Wi-Fi network or the registration.

If it still fails, follow Apple’s order and wait two minutes between steps: 1) check Settings > Cellular > (line) > Wi-Fi Calling is on; 2) restart the iPhone; 3) join a different Wi-Fi network; 4) turn Wi-Fi Calling off and on again; 5) Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings. The last step wipes saved Wi-Fi passwords, and Apple suggests contacting the carrier before working through these steps.

Wi-Fi Calling option not showing: work through the causes

Should you leave Wi-Fi Calling on, and how do you turn it off?

For most people it is fine to leave it on. iPhone only uses Wi-Fi when Wi-Fi Calling is available and hands the call to VoLTE if Wi-Fi drops. The benefit is clearest in condos, basements and tall buildings with weak signal, and abroad with roaming off. The drawbacks are that call quality depends on the Wi-Fi, and that while connected to Wi-Fi Calling the phone may not receive emergency alerts.

To turn it off, go to Settings > Cellular > (line) > Wi-Fi Calling and switch it off. This does not affect ordinary internet over Wi-Fi or app calls such as LINE or FaceTime, which are separate systems. Before a trip on True or dtac, leave it on, since the carrier’s setup page says to keep it switched on from Thailand.

Data eSIMs for travel, used alongside your Thai number on one iPhone