EE today said it will be the first UK mobile network to roll out full-blooded next-generation Wi-Fi calling.
Subscribers will not need to install any special apps: their phones should be able to seamlessly and automatically send and receive text messages, and make and receive calls, via wireless networks when there is no cellular network signal. You're out of luck if there's no usable Wi-Fi to latch onto, obviously.
This new feature uses part of the LTE spec that’s been a very long time coming: IP-Multimedia Subsystem (IMS), which was defined more than a decade ago.
LTE mobile broadband is an all-IP network, meaning calls and texts can go over Wi-Fi if that's available and VoLTE (Voice over LTE) is implemented. Otherwise, it will drop back to 3G for circuit-switched calls, which is useless if there's no cellular signal.
EE told us it has been working on the Wi-Fi calling service for three years. It requires support from the handset makers and the operating system builders. Roughly speaking, 4G handhelds that went on sale from mid-2014 can take advantage of the service.
This includes phones powered by Windows Phone 8.1 (such as the Lumia 640), and Android 5 (such as the Samsung Galaxy S6). Apple's iOS 8.3 can use the service when that upgrade is released to the public, but you'll need an iPhone 6/6+ or 5S.
EE is positioning Wi-Fi calling it as a not-spot fix, and as a convenience for London Underground passengers, rather than as a cost-saver. You won’t be able to use it abroad, and the minutes spent nattering away will come out of your monthly allowance – although that’s moot if you’re on EE’s 4G/LTE network as contract customers have unlimited voice minutes, anyway.
The initial launch is for ordinary folk, with businesses to follow later in the year. EE doesn’t think it will replace IP telephony in offices, for example.
In tests we found the Wi-Fi call quality to be outstanding, although you do get some funny looks (“how do you do that?!”) on the Tube.
EE told us it’s working on a more seamless integration for London Underground services. Today, the login process requires you to enter your EE account password, which is a bit silly. On a congested network, the voice quality may be less than stellar, but it should compare favourably with regular mobile calls, and is (of course) better than nothing.
If you want to know how long the industry has been talking about IMS - here’s the first mention of it on El Reg in an article from 2004. And a year later you could use Wi-Fi-to-cellular-roaming using UMA – which never caught on but is still sold as a signal boost by EE’s Orange brand.
Expect to see VoLTE on EE in the UK by the autumn. ®
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