Of all the features of the iPhone 6 and 6 Plus, the one that’s the most important — in some locations — is its ability to make calls via Wi-Fi. That’s because no carrier has 100 percent cellphone coverage and there will always be dead spots that require a “plan B” for those who need to make or receive calls or text messages when they don’t have cellular coverage.
It’s also handy when you’re out of the country because it means you can make and receive calls and texts for free on your regular phone number as long as you have a Wi-Fi connection. That sure beats paying roaming charges as high as $3 to $5 a minute in some countries or going through the hassle of buying and installing a local SIM card and requiring callers to dial a new overseas number instead of your regular number.
Another advantage to Wi-Fi calling is that — with most carriers — it doesn’t count against your number of minutes or text messages since you’re not using the carrier’s network to make the calls or send texts. There is also no data limit as has always been the case when connecting a phone to a Wi-Fi data network.
My adult son Will and his girlfriend both have T-Mobile accounts and when they visit us in Palo Alto, they wind up using our house phone to make and receive calls because our house has spotty T-Mobile coverage. The only good thing is that we get more of their attention because, even if they wanted to, they couldn’t reliably text during dinner.
But that’s about to change. T-Mobile set me up with a test account that I’ve been using with an iPhone 6 Plus and an LG Flex and, thanks to Wi-Fi calling, I’m getting great voice and texting service not only where I live, but whenever I’m in range of a Wi-Fi network. For example, I was in a building on Facebook’s Menlo Park campus last week where T-Mobile coverage happens to be a bit weak, but that didn’t bother me once I logged onto the company’s guest network.
T-Mobile has long offered Wi-Fi calling, but last week it rolled out its next generation service that, among other things, takes advantage of Voice over LTE (VoLTE) to seamlessly handoff calls between Wi-Fi and its high-speed LTE data network that is now also able to handle voice traffic.
Unlike using Skype or other voice over Internet apps on your phone, carrier-supported Wi-Fi calling enables people to reach you via your regular number and, when you make an outgoing call or text, they see your number appear on their screen. You make the call using the same dialer you use for cellular calls. It’s as if the carrier put a cell tower in your house.
Right now T-Mobile and Sprint are the only carriers to offer Wi-Fi calling across their entire network, but AT&T and Verizon are in the process of rolling it out over the next year or so.
Wi-Fi calling doesn’t work with all phones, even if the phone is able to access other data services (like the Web, email and connected apps) via Wi-Fi, though T-Mobile says that all phones sold in its stores from here on will be Wi-Fi calling compatible.
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print currently supports 18 phones, including the Samsung Galaxy S5 and the soon- to-be-released Galaxy Note, but not the iPhone 6 or any other iPhone.
There are also different flavors of Wi-Fi calling. Some phones support Wi-Fi calling, but don’t support VoLTE. Other phones, including the Samsung Galaxy S5 and the LG Flex, support both Wi-Fi calling and VoLTE, but aren’t able to hand off a call between Wi-Fi and LTE, which means that if you are on the phone at home and leave the house, the call will drop as soon as you lose your Wi-Fi signal.
Still, they do work as long as you stay within your Wi-Fi network as I experienced with the LG Flex that T-Mobile loaned me.
And then there are phones, like the iPhone 6, that support Evolved Packet Data Gateway (ePDG), which, among other things, allows for the seamless handoff between Wi-Fi and LTE.
I tested a T-Mobile iPhone 6 Wi-Fi to LTE handoff with an iPhone 6 Plus on my home Wi-Fi network and at a local coffee shop and, in both cases, I was able to establish a call from the Wi-Fi network and keep the conversation going over the T- Mobile LTE cellular network as soon as I left the building.
The service works with any Wi-Fi router, but T-Mobile is offering its customers use of a free “Personal CellSpot” router (built by Asus) that prioritizes voice calls over other traffic so if someone is streaming a movie on your network, it won’t interfere with call quality. The router also has a particularly strong Wi-Fi signal, which, unlike the router it replaced, is able to broadcast a signal to all parts of my relatively large two-story house.
While Wi-Fi calling solves the problem of not being able to use a phone in a dead spot where you have access to Wi-Fi, it’s of no use while you’re on the move so it’s still important to pick a carrier with good coverage in the places you’re likely to use your phone.