Wi-Fi Calling not showing or can't turn it on? Causes, checks and fixes

Why is Wi-Fi Calling not showing?

Wi-Fi Calling usually fails to show because the carrier has not enabled VoWiFi for that particular combination of number, package and phone model, not because the phone is broken. The menu only appears when all three line up: the carrier supports it, your package includes it, and the phone plus its firmware has the feature switched on in the carrier's profile.

The reason is that Wi-Fi Calling (technically VoWiFi) is not an app on the phone but a network service. The phone builds an encrypted IPsec tunnel over Wi-Fi to a carrier gateway called the ePDG, then registers with the same IMS core that carries VoLTE calls. The standards come from 3GPP and the GSMA (profile IR.51). So the phone must know which ePDG to reach, and the carrier must accept a registration from that number. If either piece is missing, the phone hides the menu or locks the switch.

The good news for Thai users: AIS, dtac and True are all listed on Apple's carrier features page as supporting Wi-Fi Calling and VoLTE on iPhone. If you have an iPhone on one of these three networks and the menu still does not show, the problem is more likely the line's provisioning, the package or the carrier settings than the hardware.

New to Wi-Fi Calling? Start with the basics

Menu missing vs switch greyed out: what's the difference?

Before fixing anything, work out which symptom you have, because the two point in different directions.

• Menu missing entirely (no Wi-Fi Calling entry anywhere in Settings): the carrier profile loaded on the phone does not tell it to show the feature. Typical causes are a carrier or package without support, a model that is not on the carrier's list, an imported phone running another country's firmware, or outdated carrier settings.
• Menu present but the switch is greyed out: the phone knows the feature exists, but a condition for turning it on is not met. Examples: the SIM is not active or is suspended, there is no signal or data during first activation, the phone is not on Wi-Fi, or the emergency address step is unfinished.
• Switch turns on but calls don't go over Wi-Fi: this is a different problem, usually about the Wi-Fi network itself, such as one that blocks UDP ports 500 and 4500 used by the IPsec tunnel, or a VPN in the way. That case has its own guide on Wi-Fi Calling not working.

Switch is on but calls fail? See Wi-Fi Calling not working

Cause-to-fix table: what to check and what to do

Use this table as a map. Work from the top down: the rows near the top are quicker to check and more common.

Step-by-step: what should you try first?

Go in this order and give each step a moment to settle. Apple suggests waiting about two minutes between steps, because registration with the carrier's system is not instant.

1. 11. Make sure you are looking in the right placeiPhone: Settings > Cellular (Mobile Data in some regions) > Wi-Fi Calling. On a dual-SIM iPhone, tap the line first; the switch only appears inside that line. Some iOS versions and carriers show it under Settings > Phone instead. Samsung (One UI): Phone app > three dots > Settings > Wi-Fi calling, or Settings > Connections > Wi-Fi Calling. Pixel and stock Android 14–16: Settings > Network & internet > SIMs > pick the SIM > Wi-Fi calling. Menu names vary by model and carrier.
2. 22. Confirm the line itself worksMake and receive an ordinary cellular call, and turn mobile data (4G/5G) on. True-dtac's setup page says activation needs signal and mobile data switched on. A suspended or unpaid line will not activate Wi-Fi Calling.
3. 33. Update the operating systemiPhone: Settings > General > Software Update. Android: Settings > Software update, or System > System update. Updates often ship newer carrier profiles that switch Wi-Fi Calling on for more models.
4. 44. Update carrier settingsiPhone: connect to Wi-Fi or mobile data, then open Settings > General > About. If an update is available, a prompt appears; installing takes under a minute. Apple says these updates can add features such as Wi-Fi Calling, and that a new SIM or eSIM may need the new carrier's settings downloaded.
5. 55. Restart, then reseat the SIMPower off, remove the SIM, power on, power off again, put the SIM back and start the phone. It then reloads the carrier profile from the SIM. Several Samsung owners report that a menu which vanished after an update came back this way; that is user experience, not an official procedure. With an eSIM, do not delete it; restart or toggle Airplane Mode instead.
6. 66. Reset network settingsDo this only after steps 1–5 fail. The paths and what you lose are covered in the section below.
7. 77. Call the carrierIf it still won't appear, the problem is probably on the network side. Ask the carrier to check that VoWiFi and VoLTE are provisioned on your number.

Has your carrier and package actually enabled Wi-Fi Calling?

Wi-Fi Calling needs a SIM that the carrier has provisioned for it. A carrier supporting the feature in general does not mean every number and every package gets it automatically. Conditions differ by carrier and can change, so check the official page or the call centre.

• AIS: the AIS Call Center guide tells Android users to register by dialling *399*1# or through AIS's website, while iPhone users switch it on in Settings once the carrier settings support it. If you are on Android and the menu is missing, try that registration first. We could not find a clear AIS statement on whether prepaid SIMs are included; ask 1175.
• True and dtac: since the merger, the official setup guide lives on true.th and covers both brands. Its listed conditions are an active SIM or eSIM, a supported phone on the latest software, signal and mobile data on during setup, and first activation inside Thailand. Call centres: True 1242, dtac 1678.
• NT Mobile: its official page says you can switch VoLTE and Wi-Fi Calling on or off by dialling *834#, and that both prepaid and postpaid customers can use it. Call centre: 1888.
• Foreign SIMs and eSIMs: every carrier sets its own policy. Some limit Wi-Fi Calling to postpaid plans or to phones sold through them. If the menu is missing with a foreign SIM, ask that carrier directly.

One case people forget: a SIM with no phone number, such as a data-only travel eSIM. It has no voice service in the first place, so there is no Wi-Fi Calling switch for that line, and that is normal. The Wi-Fi Calling you want is the one on your own Thai number.

Why is Wi-Fi Calling missing on an imported phone?

Imported phones are one of the most common reasons for a missing menu on Android. Carrier-linked features such as VoLTE and Wi-Fi Calling are switched on or off by configuration files that ship with the firmware, not by the hardware alone.

• Samsung uses a CSC (Country/Carrier Specific Code) to set features per country or carrier. A phone running another country's firmware may have no profile for AIS, True or dtac, so the Wi-Fi Calling menu does not show even though the modem can do it.
• Other Android phones (Pixel, Xiaomi, OPPO, vivo, realme): the phone loads carrier configuration based on the network code in the SIM (MCC/MNC). If the firmware has no VoWiFi entry for that carrier, the menu stays hidden.
• Carrier-branded phones from abroad (for example, contract phones from a US or Japanese carrier) often enable Wi-Fi Calling only for the original carrier's SIM. Even after unlocking, the menu may not appear with a Thai SIM.
• iPhone: this is much rarer, because Apple delivers carrier settings based on the SIM you insert, not the country of purchase. If an imported iPhone shows no menu with a Thai SIM, update the carrier settings and iOS first.

What you can do with an imported phone: update it fully, reseat the SIM, and ask the brand's Thai service centre whether that exact model code supports VoWiFi on Thai carriers. We don't recommend flashing firmware or using unofficial apps to edit network configuration; it can void the warranty, break the phone or stop emergency calls from working. If you haven't bought the phone yet, check the model against the carrier's list first.

See which phones support Wi-Fi Calling

How do you update carrier settings and check Wi-Fi Calling status?

iPhone

Open Settings > General > About and look at the number next to Carrier; that is your carrier settings version. If an update is available, an install prompt appears on its own. If nothing appears and you are unsure, Apple suggests asking the carrier whether your version is the latest. After updating, restart and check Settings > Cellular again.

When Wi-Fi Calling is active, Apple says you'll see Wi-Fi after the carrier name in the status bar or Control Center. If the switch is on but you never see it, registration has not succeeded.

Android and Samsung

Android has no separate carrier settings button; carrier configuration arrives with system updates. Samsung: Settings > Software update. Pixel: Settings > System > System update. Restart afterwards. To see IMS registration on many Android phones, dial *#*#4636#*#* in the Phone app and look for IMS Service Status, which shows whether VoLTE and Wi-Fi Calling are registered. The code does not work on every model and is a testing menu, not an official user feature, so don't change other values there.

Google also notes that when the phone detects a Wi-Fi Calling problem it turns the feature off until the problem is fixed, and if it keeps happening you'll get a notice that it has been turned off. Google's suggested fix is to restart the device or contact the carrier to re-activate it. That explains the common report of Wi-Fi Calling that used to work and then switched itself off.

Will resetting network settings bring Wi-Fi Calling back?

It helps when the problem is stuck network configuration on the phone, such as a menu that vanished after an update, or a switch stuck grey even though the carrier confirms your line is provisioned. It won't help if the carrier or package never supported the feature. Apple lists it as the last step before contacting the carrier.

• iPhone: Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings
• Samsung: Settings > General management > Reset > Reset network settings > Reset settings
• Pixel and stock Android: Settings > System > Reset options > Reset mobile network settings (with a separate entry for Bluetooth and Wi-Fi)

What you lose: saved Wi-Fi passwords, paired Bluetooth devices and any VPN or APN settings you added; you'll need to reconnect them. Photos, apps and personal data stay. If you use an eSIM and the phone asks whether to erase it as well, choose not to; erasing an eSIM removes that line from the phone. Write down the Wi-Fi passwords you need first, and don't do this abroad without a backup Wi-Fi you can rejoin.

When should you call the carrier, and what should you tell them?

If updating, restarting, reseating the SIM and resetting the network haven't worked, call the carrier. The VoWiFi flag on their side is invisible to the phone and you can't change it yourself. Apple and Google both give this as the final step.

Have this ready so you only call once: phone model and model code, OS version, carrier settings version (iPhone), IMEI, SIM type (physical or eSIM, prepaid or postpaid), package name, and whether the menu is missing or greyed out. Ask them to confirm VoLTE and VoWiFi are enabled on your number, and to refresh the provisioning if they already are.

• AIS: 1175
• True: 1242
• dtac: 1678
• NT Mobile: 1888

These numbers are for calling from your own line inside Thailand. From abroad, use the overseas contact route listed on the carrier's website or app, such as in-app chat, which works over Wi-Fi.

Already abroad and Wi-Fi Calling won't show: what now?

This is the hardest situation, because Thai carriers generally require first activation inside Thailand. Try the following in order.

1. If the menu exists but you never switched it on: try enabling it while on Wi-Fi. If it stays grey or fails, the first-activation-in-Thailand rule is the likely reason, not a fault.
2. If it was on before and has now disappeared: don't reset the network or remove the SIM. Turn on Airplane Mode, turn Wi-Fi back on, wait a few minutes and look for Wi-Fi next to the carrier name. Try a different Wi-Fi network too; True-dtac notes that some Wi-Fi networks abroad may not work with Wi-Fi Calling.
3. Contact the carrier through in-app chat or its online channels and ask whether they can enable it from their side. Sometimes they can; sometimes you'll need to wait until you're back in Thailand.
4. Meanwhile, use internet calling apps such as LINE or WhatsApp to reach people on the same app, and turn on roaming only when you must receive an important SMS or call, after checking your carrier's rates.

If you use a travel eSIM: esimonline eSIMs are data-only and have no phone number, so Wi-Fi Calling only ever runs on your own Thai number. Whether your Thai line's Wi-Fi Calling can ride on the travel eSIM's mobile data in a dual-SIM phone depends on the phone and the carrier, and we found no official AIS, True or dtac page confirming it works. Don't plan around it. Plan on Wi-Fi Calling over real Wi-Fi, and set it up and test it before you leave Thailand.

Set up Wi-Fi Calling before you travel, step by step

Set up dual SIM so your Thai number and travel eSIM work together