One of the main draws of phone networks that integrate Wi-Fi technology like Google's Project Fi and Republic Wireless -- in addition to offering customers a cheaper alternative to regular phone plans -- is they will seamlessly switch your phone service between cellular and Wi-Fi when needed.
Wi-Fi calling is nothing new. Apps such as Skype, and make it easier to use a phone to place calls and send texts over the internet and forgo mobile networks altogether. Carriers are also adopting Wi-Fi calling themselves. Whether it's because they want to bolster their network coverage or improve user experience, several networks have phones that have this service baked in.
To help you make sense of what Wi-Fi calling is, why it's important and what you can use it for, CNET put together a handy guide to walk you through everything you need to know.
Editors' note, Sept. 20: This article was originally published on Oct. 8, 2015 and has since been updated.
What is Wi-Fi calling?
Instead of using your carrier's network connection, you can make voice calls via a Wi-Fi network. That could mean using a Wi-Fi connection you have set up at home, or whatever Wi-Fi hotspot you happen to be on when you're out and about, such as at a cafe or library. In most ways, it's like any other phone call, and you still use regular phone numbers.
Why would I want that?
Wi-Fi calling is especially useful when you're in an area with weak carrier coverage. For example, when you're traveling to the residential countryside, or you're in a building with spotty reception. You may already be familiar with using Wi-Fi to send messages when SMS texting is unavailable (apps like Kik and Facebook Messenger provide these services) -- and the same applies when you're trying to place a call. With Wi-Fi, you can call a friend up even if you're in a dingy, underground bar (assuming you can connect to the bar's Wi-Fi, that is).
Isn't that what Skype does?
In a way, yes. There are various services including Skype, Viber, WhatsApp andthat provide what's known under the umbrella term VoIP, for "voice over Internet Protocol," to make calls with either a Wi-Fi or data connection.
Carrier-branded Wi-Fi calling is different, however. It's baked directly into the phone's dialer, so you don't need to fire up an app or connect to a service to use it. You can set it as your default way of placing a call, or if you lose phone signal, it will automatically switch to Wi-Fi calling.
Because the service is built in, that also means you don't need to add contacts to a service as you do with Skype. You'll have access to your existing phone book, and your friends can receive your Wi-Fi call without needing to download a third-party app. With no contacts to add, carrier Wi-Fi calling requires little effort to set up.
What carriers and phones support this service?
All four major US carriers (Google Project Fi provide Wi-Fi calling on certain phones too. The former carries , while five phones (including the , and ) work on the latter. Republic Wireless gets support from Sprint's network if connection is unavailable, while Google uses T-Mobile, Sprint and US Cellular.
All of T-Mobile phones offer Wi-Fi calling built-in. As for Sprint, Wi-Fi calling is available on a number of iPhone models that run iOS 9.1 or higher. Several Android devices have the service as well, but you'll need to check through your phone's Settings menu to see if you have it. AT&T offers Wi-Fi calling for 23 phones, while Verizon has 17 phones in its Wi-Fi lineup.
Does it cost more?
For domestic calls, it doesn't cost any extra as such. But making calls over Wi-Fi can come out of your regular minutes allowance depending on your carrier and your phone plan. Be sure to read the policies of your carrier to see if any of their potential restrictions and charges relate to your situation. Click the following to read the restrictions for T-Mobile, Sprint, AT&T and Verizon.
If you're running out of minutes, using services like Skype or WhatsApp will help avoid incurring any additional charges.
Can I use it overseas without huge bills?
Again, that depends. T-Mobile lets you make and receive Wi-Fi calls for free between more than 140 countries. Sprint customers can call from over 200 countries but there are some exclusions (Australia, China, Cuba and others). Also, four of its Android phones don't support international Wi-Fi calling: the , , and .
Unless you have an iPhone running iOS 9.3, both AT&T and Verizon charge for international Wi-Fi calls, whether you buy an international plan or pay per use.
Republic Wireless only supports Wi-Fi calling for the US and Canada. You can make calls to Puerto Rico, Guam, US Virgin Islands, American Samoa, Northern Mariana Islands, Johnston Atoll, Midway Atoll and Wake Island, however, but may be charged 50 cents per minute. Project Fi works in more than 135 countries, but you should check specific rates depending on the country you're calling to and from. You'll also only be charged for outbound calls.
If you're, it's best to stick with Skype and WhatsApp when you're connected to a building or hotel's Wi-Fi. You can use data, but remember that it will cost you a lot if you're roaming on cellular networks. If you don't have a roaming plan, make sure you only use Wi-Fi and turn off data roaming in your settings before heading out.
Do I need a fast Wi-Fi connection?
Though the higher throughput you have the better your connection will be, a minimum of 1Mbps should be enough to patch a solid call through. Republic Wireless reports that it can hold a call with 80Kbps, but the quality may decrease and you'll experience more dropped calls as well.