Does Wi-Fi Calling cost money? How Wi-Fi calls are billed at home and abroad
Wi-Fi Calling is not free, but it has no sign-up fee either: calls come out of your Thai plan's minutes just like normal calls. This guide walks through each case — calling inside Thailand, calling home from abroad, calling foreign numbers, the Wi-Fi data itself — and compares it with LINE and WhatsApp calls.
Quick answer
- Wi-Fi Calling has no separate sign-up or monthly fee, but outgoing calls are billed like normal calls under your current plan: they use your package minutes or prepaid balance.
- When you are abroad and call a Thai number over Wi-Fi Calling, it is billed at your package rate as if you were in Thailand, not at voice-roaming rates, and True-dtac states that you do not need to turn on roaming.
- Calls to foreign numbers over Wi-Fi Calling are still charged as international calls under your plan, and the data comes from whatever Wi-Fi you are on. For truly free calls, use LINE or WhatsApp, which cost only data.
Does Wi-Fi Calling cost money?
Yes, but not as an extra charge: Wi-Fi Calling is billed like a normal call under your number's current plan. The feature itself has no sign-up fee. What you pay for is the call minutes that get deducted, plus the Wi-Fi data if that Wi-Fi costs money.
Many people assume "calling over Wi-Fi = free calls" because they mix it up with app calls such as LINE or WhatsApp. In fact, Wi-Fi Calling (technically VoWiFi) is not a chat app. It is a call made with your own mobile number; only the path changes, from the mobile tower to the Wi-Fi internet connection. The call still goes into your carrier's system (AIS, True, dtac or NT), and the carrier still bills it under your plan as before.
The technical reason: 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 handles VoLTE calls on 4G, following 3GPP standards and the GSMA IR.51 profile. To the billing system, a call arriving over Wi-Fi is a call from your number like any other.
How is Wi-Fi Calling billed, and what does each Thai carrier say?
Wi-Fi Calling billing breaks down into three parts: (1) outgoing calls, deducted from your package minutes or prepaid balance at the same rate as a call over the mobile network; (2) incoming calls, which follow the Thai mobile rule that the caller pays; (3) the data that carries the call, which comes from the Wi-Fi rather than your plan's mobile data. On home Wi-Fi or free Wi-Fi this adds almost no cost.
Below is what each carrier's official page actually says as of the date we checked (27 Sep 2026). We do not list per-minute prices because the rate depends on each person's package.
| Carrier | What the official page says about charges | Also worth knowing |
|---|---|---|
| True / dtac | Charged like a normal call at your current package rate; works on both postpaid and prepaid | No need to turn on roaming service abroad, but Wi-Fi Calling must be turned on while still in Thailand |
| AIS | AIS's how-to page lists no separate price; it only says you can make and receive calls on your Thai number over Wi-Fi in Thailand and abroad | AIS advises turning on Airplane Mode and checking for the AIS WiFi Call symbol before calling, so the call does not go out as voice roaming at the regular rate |
| NT Mobile | Outgoing domestic and outgoing international calls are billed under your package; incoming calls, both domestic and international, are free | Works on both postpaid and prepaid; turn it on or off with *834# |
Summarised from the True-dtac, AIS and NT official pages opened on 27 Sep 2026. Per-minute rates depend on your package; confirm with your carrier.
For AIS, the page we opened does not state a figure, but its warning about "voice roaming at the regular rate" implies that calls over Wi-Fi Calling are not billed at roaming rates, and users on Pantip report that minutes are deducted from the package like a normal call. We did not find a written confirmation of this on an AIS page itself, so if you want to be sure, ask the AIS Call Center on 1175 before you travel.
Inside Thailand, does a Wi-Fi call cost the same as a normal call?
Yes, the same. In Thailand, Wi-Fi Calling does not make calls cheaper or more expensive. If your package includes, say, 200 minutes to all networks, a Wi-Fi call comes out of those 200 minutes. If your package gives free calls within the same network, that rule still applies. When the minutes run out, extra minutes are charged at the package's overage rate. On prepaid, the call is deducted from your balance at your usual per-minute rate.
So the benefit of Wi-Fi Calling inside Thailand is not saving money but getting calls through where mobile signal is weak: basements, high-rise condos, rooms deep inside buildings. That is how the carriers market it. The data comes from your home or office Wi-Fi, which is usually a flat monthly fee anyway.
- No activation fee: none of the True-dtac, AIS or NT official pages we opened mentions a sign-up or monthly fee for the feature itself.
- It does not use your plan's mobile data while you are on Wi-Fi, because the voice data travels over the Wi-Fi.
- If you drop off Wi-Fi mid-call, the phone may hand the call over to 4G (VoLTE). Inside Thailand that is billed at the same rate, so it does not change the cost.
Abroad: how are Wi-Fi calls to Thai numbers billed?
This is where Wi-Fi Calling saves the most. When you are abroad and call a Thai number over Wi-Fi Calling, the carrier sees it as a call from your number inside its own system, so it deducts minutes from your package as if you were in Thailand, instead of charging voice roaming, which is normally far more expensive. True-dtac states plainly that you do not need to turn on roaming service to use it abroad.
Three conditions make this rate apply: the call must actually go over Wi-Fi Calling (the Wi-Fi Calling indicator shows on screen); Wi-Fi Calling must have been turned on while you were still in Thailand (True-dtac says it cannot be used otherwise); and the Wi-Fi you are on must not block IPsec connections (UDP ports 500 and 4500), which some hotel or public Wi-Fi networks do.
One more thing: if your package has limited minutes, long calls home during a trip use the same minutes you would use at home. Once they run out, you pay the package's overage rate, not a roaming rate. On prepaid you need enough balance; otherwise you cannot place calls even though Wi-Fi Calling is connected.
Do Wi-Fi calls to foreign numbers cost international rates?
Yes. Wi-Fi Calling does not change where the call goes. If you ring a Japanese, Korean or European number, it is still an international call from your Thai number. NT states outright that outgoing international calls over Wi-Fi Calling are billed under your package, which means the package's international call rate. They are not free.
The case people often get wrong is abroad: say you are in Tokyo and ring a Japanese restaurant or hotel number from your Thai line over Wi-Fi Calling. The restaurant may be one street away, but in the carrier's system the call starts in Thailand and goes to Japan, so it is usually billed as an international call from Thailand, not a local call within Japan. The Thai carrier pages we opened do not spell this out country by country, so check your package's international rates with your carrier before making many calls to local numbers.
Be careful with toll-free and special numbers too. Overseas carriers such as AT&T note that toll-free numbers may not connect, or may be billed as international calls, when dialled over Wi-Fi from abroad. The Thai carrier pages we opened do not cover this, so if you need to call such a number, try a short call and check your usage in the carrier's app.
Wi-Fi Calling costs by situation: summary table
| Situation | Call charge | Data | Watch out for |
|---|---|---|---|
| In Thailand, calling a Thai number | Package minutes, same as a normal call | Uses the Wi-Fi you are on | No saving; the gain is coverage where signal is weak |
| In Thailand, receiving a call | Free; the caller pays | Uses the Wi-Fi you are on | Nothing special |
| Abroad, calling a Thai number | Package minutes as if in Thailand, not roaming rates | Hotel/café Wi-Fi, or paid Wi-Fi | Check the Wi-Fi Calling indicator first, or you may be billed voice roaming |
| Abroad, receiving a call from a Thai number | NT says free; confirm with other carriers | The Wi-Fi you are on | If you are not on Wi-Fi Calling, the call may arrive over roaming, which charges for incoming calls |
| Calling a foreign number (from anywhere) | Your package's international call rate | The Wi-Fi you are on | Local numbers in the country you are visiting count as international too |
| Wi-Fi drops while roaming is left on | May be billed as voice roaming at the regular rate | — | Turn on Airplane Mode, then turn Wi-Fi back on |
Actual charges depend on each line's package; this table shows how billing works, not prices.
Is receiving calls over Wi-Fi Calling free?
In Thailand, receiving mobile calls is already free because the caller pays, and Wi-Fi Calling is no different. For abroad, NT is the only carrier we found that states clearly on its page that incoming calls over Wi-Fi Calling are free both at home and abroad. The True-dtac and AIS pages we opened do not address incoming-call charges abroad separately.
What is certain is that if a call reaches you over the roaming network instead of Wi-Fi Calling, answering it while roaming is charged at your carrier's roaming rate. To rule that out, turn on Airplane Mode and then Wi-Fi, so the only way a call can reach you is Wi-Fi Calling. If you do not want to pick up unknown callers during a trip, let them go to voicemail or call back on LINE instead.
What about the data? How much Wi-Fi does a call use, and do you pay for it?
Besides minutes, the other cost is the data that carries the call. Wi-Fi Calling voice uses low-bitrate codecs such as AMR-WB or EVS. Guides from eSIM providers and calling apps estimate roughly 0.5–1 MB per minute for a voice call (about 5–10 MB for a 10-minute call). That is an approximation, not a published 3GPP or GSMA figure, and it varies with voice quality and network conditions.
- Home, office, hotel or café Wi-Fi that is free to use: practically no extra cost.
- Paid Wi-Fi such as on planes, cruise ships or hotels that charge by the day: you pay the Wi-Fi owner, and you still pay your mobile carrier for the call under your package. Many airlines do not allow voice calls over in-flight Wi-Fi anyway.
- Hotspot from another phone: the call's data comes out of the mobile data of the phone sharing the hotspot.
- Video calling over Wi-Fi (where the carrier and phone support it) uses several times more data; the same sources estimate about 6–8 MB per minute.
For people using a data-only travel eSIM alongside a Thai SIM in a dual-SIM phone: some models can let the Thai line's Wi-Fi Calling ride on the other SIM's mobile data (Apple and Samsung have related settings), but the Thai carriers do not document support for this on the official pages we opened, and Pantip users report results that vary by carrier and phone model. If it works, the call is still charged to your Thai package, and the call's data comes out of the travel eSIM's allowance. Test it before you leave and do not rely on it for important calls.
Wi-Fi Calling vs LINE / WhatsApp calls: which is cheaper?
If the person you are calling has LINE or WhatsApp and is online, an app call is cheaper, because it uses no call minutes at all, only data. But Wi-Fi Calling does things the apps cannot: it can call any number, including landlines, banks and people without the app; the other side sees your phone number; and people who call your Thai number can reach you while you are abroad.
| Compared | Wi-Fi Calling | LINE / WhatsApp call |
|---|---|---|
| Call charge | Package minutes or balance | No call charge; data only |
| Who you can call | Any number: mobiles, landlines, banks | Only people with the same app who are online |
| What the other side sees | Your phone number | Your app account name |
| People calling your Thai number | Reach you over Wi-Fi | Not covered; they must call via the app |
| Needs a carrier-enabled SIM | Yes: the Thai SIM must be in the phone with Wi-Fi Calling on | No; any internet connection works |
| Roaming-charge risk | Yes, if Wi-Fi drops while roaming is on | No voice roaming, but roaming data is charged if you use it |
Use LINE/WhatsApp for people who have the app, and keep Wi-Fi Calling for numbers that need a real phone call.
The mix that works for most travellers: talk to family and friends on LINE, which uses no minutes, and use Wi-Fi Calling to call hospitals, banks, airlines or Thai offices that are not on LINE, and to receive calls to your Thai number, such as a bank officer or a courier following up on a parcel.
Who saves the most money with Wi-Fi Calling?
Pros
- Travellers and people working abroad who must call Thai numbers that are not on LINE, such as banks, hospitals or government offices: they pay package minutes instead of voice roaming.
- People who need to receive calls on their Thai number during a trip: they can answer over Wi-Fi without turning on roaming.
- People who have unused minutes on a monthly plan: calls from abroad use minutes they have already paid for.
Cons
- People who talk to family for a long time every day: if the other side has LINE or WhatsApp, app calls are cheaper.
- People who often call local numbers in the country they are visiting: they may pay international rates, so a local SIM with a number or a calling app may work out cheaper.
- People in Thailand hoping to save money: at home it costs the same as a normal call; the gain is only coverage.
How to check you are really on Wi-Fi Calling and not paying roaming
- 1Turn on Wi-Fi Calling while still in ThailandiPhone: Settings > Cellular (or Mobile Data) > Wi-Fi Calling; on dual-SIM phones pick the Thai line first. Android: usually Settings > Connections or SIM cards & mobile networks > Wi-Fi Calling, or in the Phone app > Settings. Menu names vary by model and carrier. AIS customers on Android register with *399*1#.
- 2On arrival, turn on Airplane ModeAirplane Mode cuts all mobile network connections, so the Thai line cannot place calls over roaming. Then turn only Wi-Fi back on.
- 3Wait for the Wi-Fi Calling indicatoriPhone shows "Wi-Fi" next to the carrier name in Control Center; AIS customers see AIS WiFi Call; Android usually shows a phone-and-Wi-Fi icon in the status bar. If it does not appear, try another Wi-Fi network, because some networks block Wi-Fi Calling.
- 4Make a short test call and check your usageCall a Thai number for about a minute, then open your carrier's app or ask its call centre, and check that minutes were deducted from the package as usual with no new roaming charge.
If you also want mobile data on the trip, use an eSIM or local SIM for data and keep data roaming off on the Thai line. Whether to keep the Thai line's cellular signal on depends on how much voice-roaming risk you accept. If you want zero risk, switching the Thai line off in the dual-SIM settings and using Wi-Fi Calling only while on Wi-Fi is the safest route.
Frequently asked questions about Wi-Fi Calling costs
FAQ
Are Wi-Fi Calling calls free?+
No. Wi-Fi Calling charges calls like normal calls under your number's package. What it does not have is a sign-up or monthly fee for the feature. For truly free calls, use an app such as LINE or WhatsApp, which only costs data.
Is there a fee to turn on Wi-Fi Calling?+
The True-dtac, AIS and NT official pages we opened do not list a sign-up or monthly fee. True-dtac and NT say it works on both postpaid and prepaid, with calls billed under your current package.
Abroad, am I charged roaming when I call Thailand over Wi-Fi Calling?+
If the call really goes over Wi-Fi Calling, it is billed at your package rate as in Thailand, not at roaming rates, and True-dtac says you do not need roaming turned on. But if the Wi-Fi drops while the Thai line is still on the mobile network, the call may go out as voice roaming at roaming rates, so turn on Airplane Mode first.
Does it cost money to receive calls over Wi-Fi Calling abroad?+
NT states clearly that incoming calls over Wi-Fi Calling are free both at home and abroad. The AIS and True-dtac pages we opened do not say this separately, so ask your carrier before you travel. What is certain is that if the call arrives over roaming instead of Wi-Fi Calling, you pay roaming charges for receiving it.
Is calling a foreign number over Wi-Fi Calling cheaper than a normal call?+
Generally not, because it is still billed as an international call at your package's rate. NT writes that outgoing international calls over Wi-Fi Calling are billed under your package. If you call abroad often, compare an international calling add-on or a free calling app.
If I am in Japan and call a Japanese number with my Thai line's Wi-Fi Calling, how is it billed?+
In the Thai carrier's system the call starts from your Thai number, so it is usually billed as an international call from Thailand to Japan, not a local call within Japan. The Thai carriers do not detail this case on the pages we opened, so check your package's international rate first. If you need to call shops or hotels often, a local SIM with a number may be cheaper.
Does Wi-Fi Calling use my plan's mobile data?+
While you are on Wi-Fi, the voice data goes over the Wi-Fi and does not use your plan's mobile data. eSIM providers estimate a voice call at roughly 0.5–1 MB per minute, which is an approximation. If you are on another phone's hotspot, the data comes out of that phone's mobile data.
Can prepaid SIMs use Wi-Fi Calling, and how are they charged?+
True-dtac and NT say it works on both postpaid and prepaid; calls are deducted from your balance at the package's per-minute rate, as with normal calls. The AIS page we opened does not state clearly whether prepaid is included, so check on 1175. Top up enough before you travel, because you cannot place calls once the balance runs out.
Which is cheaper, Wi-Fi Calling or a LINE call?+
If the other person has LINE and is online, a LINE call is cheaper because it uses no minutes, only data. Wi-Fi Calling is the better choice when you need to call a number that is not on LINE, such as a bank or hospital, or when the other side needs to see your real number.
If I use a travel data eSIM and make Wi-Fi Calling calls on my Thai number, what do I pay for?+
The call charge always comes from your Thai line's package, because the travel eSIM is data-only with no phone number. If your phone lets Wi-Fi Calling run over the eSIM's data, the call's data comes out of the eSIM, but the Thai carriers do not confirm this setup on the official pages we opened. Test it first and use real Wi-Fi for important calls.
Why was I charged roaming even though I used Wi-Fi Calling?+
The usual cause is that the call did not actually go over Wi-Fi Calling: the Wi-Fi was weak or blocked Wi-Fi Calling, so the phone used the local mobile network instead, or the Thai line was using roaming data. To prevent it, turn on Airplane Mode, turn Wi-Fi on, check for the Wi-Fi Calling indicator before every call, and keep data roaming off on the Thai line.
Sources
- Wi-Fi Calling settings and charges (True-dtac) — True Corporation, September 27, 2026
- WiFi Calling (VoWiFi) service and rates — NT (National Telecom), September 27, 2026
- AIS Wi-Fi Calling on iOS: how to register and use — AIS Call Center, September 27, 2026
- Make a call with Wi-Fi Calling — Apple Support, September 27, 2026
- Learn about international Wi-Fi calls — AT&T, September 27, 2026
Instagram and TikTok have no web share button, so we open your phone's share sheet or copy the link instead.
Related
- What is WiFi Calling? How it works and how to use it, explained simply
- Does WiFi Calling work abroad? Calling home to Thailand and what it costs
- Does Wi-Fi Calling use data? How much per minute, and do you need Wi-Fi the whole time
- AIS Wi-Fi Calling: how to activate it, set up your phone, check support and use it