When we landed at MLE, I got a text message from T-Mobile warning me I was not in a Simple Choice country, and that extra charges could apply. I was aware of that already, turned off "Cellular Data," and turned on "Airplane Mode." I accessed the wifi of the resort where we were staying. The phone rep spent a fair amount of time researching it herself, said she'd been unaware, and suggested avoiding such charges by making phone calls through Skype instead of T-Mobile.

I'm still confused about it.

Initially I thought that the calls Fredd made must have gone out over the local cellular network - T-Mobile's website confirms the $5.99/minute rate - but now I'm not too sure. Fredd, can you check your previous bills to see if the call Type was listed as (R) (W)? As I looked at my bill for my most recent trip abroad (September/October 2014), I saw the following for some of the WiFi calls placed:

1. Incoming to Taiwan (Wi-Fi Call) (R) (W)
2. Taiwan (Wi-Fi Call) to GRAND RPDS, MI (R) (W)
3. Guam (Wi-Fi Call) to LOS GATOS, CA (R) (W)
4. Hong Kong (Wi-Fi Call) to GRAND RPDS, MI (R) (W)

Type: (R) Roaming (W) Wi-Fi Call

Contrast this to the days before the Simple Choice changes where these calls would just code as (U), HotSpot Call. The change from (U) to (W) happened on my March 2014 bill. However, on a trip abroad in February 2014, the two WiFi calls that I placed only showed (W), not (W) (R). Likewise, in June I only saw (W).

I think the problem came in when T-Mobile introduced the new bill format in July 2014. I can't confirm this is when WiFi calls abroad started showing as roaming as I didn't leave the US between June and September.

This is certainly a departure of the advertised WiFi calling feature, which implies you'll never be charged additional fees for placing stateside calls (or any calls included with your plan) via WiFi. Even before the days of Simple Choice I used WiFi calling and texting successfully all over the place (and in some remote locations where the roaming rates would have been astronomically expensive) and was never charged as long as the call went out over WiFi.

Finally, texts made via WiFi don't seem to be billed as roaming.

I'm now fairly certain there is an error with T-Mobile's billing of WiFi calls made overseas and that you in fact did made these calls using WiFi calling. Can you check to see the call Type for the calls to Canada made in the Maldives? Were they Type (W) (R)? If that is the case, there is a billing issue that I want to bring to the attention of TmoNews.

Majuki, I have checked now and they're definitely listed as follows:

Maldives (Wi-Fi Call) to VICTORIA, BC (R) (W) 32 (Min) $191.68

It was a surprise to me on other wifi calls in places such as Sri Lanka, Thailand and Malaysia to find out I'm paying 20 cents a minute to T-Mobile. If that's the case, I suppose it's logical that they charge me the high rate for such countries as The Maldives.

I would have thought that making a wifi call with T-Mobile would be just the same as calling domestically, i.e. free but I suppose that's my own ignorance. But if I'm still paying 20 cents a minute, what's the advantage of calling using wifi as opposed to the foreign cell towers?

While in the Maldives I was also billed 50 cents each for a total of five texts marked "Roaming - Text" that I sent to Sri Lanka, Canada, and the U.S.

Were the calls placed in Sri Lanka, Thailand, and Malaysia to the USA or to Canada as well?

With the current roaming rates, it's the same 20¢/minute if you're calling from a Simple Choice country to a non-US number included in Simple Choice - eg) Hong Kong to Taiwan - so it makes no difference if you use the cellular network or WiFi. In this scenario, it's better to place the call over the more reliable cellular network than WiFi if you're going to be charged the same price. However, if you're calling Hong Kong to the USA, then it makes more sense to use WiFi since there is no charge over WiFi vs. 20¢/minute when using a mobile network in Hong Kong.

You weren't ignorant. Making a WiFi call with T-Mobile should be no different than calling domestically if you're calling a stateside number (or an international number if you have an international calling plan). Historically, this has 100% been the case. The change seems to have happened in July when T-Mobile changed its bill format. Whether or not this was an intentional change is unknown.

So you don't need a special router for Wifi calling, as long as you have a compatible phone and OS, it will just work?

I have weak T-Mobile signal at home.

They were all placed to Canada. I reviewed the four bills I've received since acquiring an iPhone 6 Plus and as it happens I haven't yet made a WiFi call to the U.S.

It seems sensible for me to use Skype then if possible, as even the bargain rate 20 cents per minute starts to add up if "chatting" for 20-30 minutes.

Thanks. I've just quoted you as an expert witness to Mrs. Fredd. :D

That would have been my impression. I'm still a very happy and satisfied T-Mobile customer but it's good to realize that T-Mobile WiFi calls don't necessarily translate into free calls.

I appreciate the information you've provided. ^

An afterthought: My impression after talking to the rep was that it was T-Mobile charging me the $5.99 per minute for my calls in the Maldives. If they had been billed by a Maldivian phone company I doubt they would have volunteered to reverse the charges.

I'll relay that to Mrs. Majuki. :D

This is correct. T-Mobile was the one to terminate the WiFi call in the US from Canada. The local mobile network in the Maldives took no part in the transaction. I still think this is a billing issue with T-Mobile, but there haven't been very many test cases.

Here's the deal though. WiFi calls should be the same cost as calling using a T-Mobile USA tower. So, in your case, assuming you don't have an international calling plan, calls to Canada from the US are normally $0.49/minute. My theory is that they implemented the billing this way to avoid discrepancies that would otherwise exist while roaming in a Simple Choice country.

Consider the following example that assumes you're a Simple Choice customer without an international calling plan:

If you were in Australia, a Simple Choice country, and decided to call Canada over the mobile network the price is 20¢/minute. If you decide to call Australia over the mobile network the price is 20¢/minute. If you decide to call the USA over the mobile network the price is 20¢/minute.

However, if T-Mobile were to treat WiFi calls as calls originating from the US, which they technically are, then the calls placed over WiFi in Australia to Canada, Australia, and the US would be 49¢/minute, $1.99/minute, and 0¢/minute, respectively.

I don't know how the billing is setup technically. My suspicion is that they're going off of the last point of contact that they had from when your phone was connected to the local cellular network. For instance, if you last connected to a mobile network in the Maldives, they would assume you're in the Maldives. The only other way is to do a lookup of the lessee of the IP address, but if I had to guess they're determining the governing rate for WiFi calls via the first way. If this is the case, this could conceivably lead to the scenario where you flip your phone into airplane mode/WiFi calling mode, make a call home, depart from Male, arrive home in Seattle, turn your phone back on at home, have the phone start making WiFi calls from your home network, and get charged outrageous roaming rates even though you're in the US!

Now, I haven't tested out all of these scenarios, and I've only called stateside numbers via WiFi while abroad. I have called international numbers but only over the mobile network. I will be going to Hong Kong in January and will be able to test to see if I get charged placing a call over the WiFi network to a number in Hong Kong. I subscribe to an international calling plan, so I shouldn't be charged.

I think T-Mobile is simply using the billing rate for the location from which they think you're placing the call. Perhaps WiFi calls from the Maldives back to the US wouldn't be charged the roaming. For instance, if it looks to see if there's a roaming/LD charge associated with the WiFi call only then will it look up and bill you the roaming rate. If it's setup this way, then T-Mobile subscribers using WiFi calling in the Maldives would not see roaming charges if calling to the US, but you would have because you called Canada. The billing system used the Maldives roaming rate to charge the call when you should have been charged $0.49/minute.

I'm going to bring this to the attention of TmoNews. I think the reason why we haven't seen any reports of this so far is that the vast majority of T-Mobile subscribers are calling US numbers via WiFi while abroad.

This is an interesting case for sure...

Thanks for a very plausible explanation. ^ If you find out anything more about this issue, I for one would be very interested in an update.

I'll keep the thread updated. I've sent an e-mail to the editor of TmoNews. We'll see what comes of it. ^

And I'm curious to see now how it would work over wifi in a foreign country if you have the new international calling plan.

I also wonder if the billing system is wonky maybe you can connect your phone to a stateside Vpn so the Tmo server would think you're in the us.

I'm also curious about these scenarios. I think, however, that the billing doesn't depend on how the IP address, so a VPN wouldn't work. This goes back to my earlier comment that it is conceivable that such a scenario where you're charged a $5.99/minute roaming rate could occur if you had the phone in airplane mode from MLE and ended up back stateside and started making calls over WiFi. I have further evidence that might support this:

When I was in Guam in September I had the following calls:

1. 9/25 to GRAND RPDS/MI (W)
2. 9/25 to Guam (Wi-Fi Call) to GRAND RPDS/MI (W) (R)
3. 9/25 to Guam (Wi-Fi Call) to GRAND RPDS/MI (W) (R)
4. 9/25 to GRAND RPDS/MI (W)
5. 9/28 to TAIWAN (J)
6. 9/28 to GRAND RPDS/MI (W) (R)

J is the international discounted calling for which I was charged $0.18/minute. I suspect this call was made over WiFi - but I don't remember - since if it had gone out over the cellular network it would have been $0.20/minute. However, it doesn't explain why for some WiFi calls T-Mobile thought I was "roaming" but not for others.

I think you're mixing apples and oranges.

The 'new' international calling plan applies for calls originating stateside to ~30/70 countries [mobile/landlines]. The earlier international program was all calls originating overseas to ~120+ countries -- charged at $0.20/minute.

Wifi calling is free only to calls to a USA number, regardless of call origin. This is great when overseas and calling stateside on wifi. Canada doesn't count as USA for wifi calling. Wifi calling to any non USA number is charged based on call origin: if from overseas, $0.20/minute, if from USA and you sign up for new international calling plan, free to the qualifying ~120+ countries. And you don't sign up for new plan, then at the much higher international roaming rates.

Is the audio quality of Wifi calls better, regardless of what kind of signal you can get?

I'm thinking of switching from AT&T to T-Mobile. I get bad reception at home for both, though they're about the same in most of the places I frequent.

I guess if I traveled more in the US, especially outside of major metro areas, I could regret switching.

My post above cites a counterexample. I was in Guam and when my wife called Taiwan via WiFi we were billed at $0.18/minute. (We have the international calling plan.) While Guam is the US and part of the NANP, it's outside of T-Mobile USA's service area. When placing and taking calls over the cellular network we were billed $0.20/minute.

What we're saying is that billing someone $5.99/minute for calling Canada from the Maldives via WiFi (when the call is terminated by T-Mobile in the US) is ridiculous. A VoIP call presents the same to T-Mobile regardless of where the call originates; it's simply data. For these purposes a WiFi call should be billed as if the call originated over T-Mobile USA's own network.

Now, the reason why it is no longer billed this way - it certainly used to be - is unclear. I speculated above that the reason was to harmonize the costs associated with calling abroad while in a $0.20/minute location. You wouldn't want WiFi calls to be costing more than calls going out over the cellular network, so I am guessing T-Mobile tried to simplify billing by tying the per minute rate to the cellular rates for the origin country. In doing so they created this corner case that Fredd hit upon.

For example, had Fredd placed a call to Canada from the US over T-Mobile USA's cellular network, the per minute rate would be $0.49. Had he placed a call in the US over WiFi to Canada the per minute rate would be $0.49. Had he placed a call over Bell's network in Canada to a Canadian number, the cost would be $0.20/minute.

However, the discrepancy comes in where you go to place a WiFi call in Canada to Canada. We already know that if it goes out over the cellular network it would be $0.20/minute. However, if we were to continue to treat all WiFi/UMA calls as originating in the US, then the cost would be $0.49/minute, the same as if you were calling from the US to Canada. To avoid this discrepancy and harmonize the rate, I am guessing T-Mobile is simply using the current country as the billed rate, which resulted in the $5.99/minute charge in the Maldives.

The problem here is that while I don't doubt T-Mobile incurs extra costs when one of its subscribers uses a mobile network in the Maldives, when it receives a WiFi/UMA call, it doesn't matter where the call originates. It's just data routed over the Internet and the cost to receive the data is the same, regardless of whether the call originated in Male, Las Vegas, Calgary, or McMurdo Station.

This is a legitimate billing concern, and I don't think it was T-Mobile's intention to implement things this way. You can infer this from the CSR's confusion plus this would be a typical underhanded mobile carrier move, an image that T-Mobile is trying to shed.