What You Need to Know About Wi-Fi Calling

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Reception inside buildings and other structures is always an issue for cellular phones, and it has a lot to do with just the way radio signals travel. There is no easy fix other than installing what is called a repeater inside the building, which receives signals from your device and transmits it outside of the building to the closest tower.

Repeaters are costly and impractical to both set up and maintain in mass quantities, so cellular phone operators and manufacturers got creative. The most obvious alternative takes advantage of a wireless technology already present in many buildings, and that’s Wi-Fi.
How does it work, and most importantly what do you need to get started using Wi-Fi calling? This guide will answer some of your basic questions.

What is Wi-Fi calling?

Wi-Fi calling uses a Wi-Fi connection to both place and receive calls where no signal is available. This can either be your home wireless connection, or anywhere where you can find a hotspot, CNET explains. There is no difference in how you place or receive calls, the only difference is how they are routed.
Wi-Fi calling works similarly to how Skype and other Internet voice communications apps work. The call is routed through the Internet, and then at some point passed over to the traditional telephone network to complete the connection.
In most cases you will notice next to no difference in call quality between the two or even know it’s all happening over Wi-Fi, although Sprint’s FAQ does say your Android or iPhone may display a symbol in the taskbar indicating the call is being placed over the Wi-Fi network.

Won’t calls drop if I’m out of Wi-Fi range?

Yes and no. Sprint’s documentation indicates that calls placed over Wi-Fi calling on their network will drop when you’re out of range. On AT&T and T-Mobile, in some cases it may not. T-Mobile’s Wi-Fi calling primer notes that certain handsets will be able to seamlessly transfer calls between the Wi-Fi and its LTE network.
AT&T is similar, and as long as you’re in what they call “HD Voice” coverage, calls will seamlessly transfer between Wi-Fi and LTE. Wi-Fi calls appear to not be able to transfer to 3G or standard 4G service, though.
We’d recommend as a general rule to assume that it won’t, so if you’re making a Wi-Fi call, make sure you stay in range of the Wi-Fi network.

What devices support Wi-Fi calling?

Right now, any device running iOS 9 will support Wi-Fi calling. As of press time, only iPhone 6 and 6S generation devices can do so on AT&T. On Sprint and T-Mobile, there are several Android devices that may work with their service.
To see if your Android device is compatible, look for a “Wi-Fi Calling” option within your settings menu. It also may be listed in the “Key Features” tab of phone details. For both iOS and Android, you will need to turn on the feature manually, as it is not enabled by default.

What carriers support the feature?

AT&T, Sprint, and T-Mobile support Wi-Fi calling. Verizon says that it plans to support Wi-Fi calling in the future, but has said little on when it will debut or what devices it plans to support.

How much does it cost?

Wi-Fi calling is offered at no additional charge on all three networks, and in all cases do not count against your monthly allotments. However, calls placed on international Wi-Fi networks will still count as international roaming.

Can I still call 911?

Yes. Federal regulations require that you provide an address at setup that you would like to be displayed to emergency responders. Do remember that if you place a 911 call on a Wi-Fi network somewhere other than your home, you will need to provide the operator with an address so they can find you.

Will it work over a slow Wi-Fi connection?

Sprint says you will need a 1Mbps signal at a minimum to use Wi-Fi calling effectively. Even on public networks this shouldn’t be an issue as typically most hotspots guarantee speeds of at least that. It is possible that calls may go through on slower networks, but the call quality may be poor or choppy.
Use your best judgement when using Wi-Fi calling: It’s probably not a good idea to try it in a coffee shop during lunch when there are a lot of people on the network, and always make sure you’re as close to the router as possible.

This is great and all, but how well does it work?

If you understand the limitations of your carrier and have a good Wi-Fi signal, Wi-Fi calling works just like your phone would on the regular cellular network. All the carriers recommend though that you use a router compatible with 802.11n, so if you have an aging router it’s time to upgrade.
If you live in a rural area and have spotty coverage to begin with, Wi-Fi calling might be the only option to make using your phone inside your home a possibility. It’s here where this new technology really shines, and will likely be the most useful.