This blog is by Ismo Matilainen at Nokia Networks.
There has been growing debate about the Voice over WiFi (VoWifi) technology for many months, but with the launch of the iPhone 6 and its native support for VoWiFi, the discussion has stepped up several gears. The Apple effect strikes again!
The ability to make voice calls over WiFi has been available in networks for years. But now it’s all about doing it in a more telecom-minded way – in other words, making it both easy and convenient.
Operator-managed VoWiFi, as implemented in the iPhone 6 and some other smartphones, is certainly a leap ahead of over-the-top (OTT) implementations in terms of simplicity for the user. Unlike OTT versions that can be so frustrating, making a VoWiFi call is as easy as making a normal mobile call, using the phone’s standard dialer and normal phone. But there’s nothing better than hands on experience, so I popped over to Nokia’s R&D laboratory to experiment with a VoWiFi call connecting to a VoLTE-enabled phone over an LTE network. The result was the same as making a normal VoLTE call: one second call setup time and excellent voice quality.
Another aspect to convenience that has been brought into question is the perceived need for seamless handover from a VoWiFi call to the cellular network. A solution is available, but how often will people make calls at home over WiFi and then mid-conversation leave their houses or apartments? Not often I suspect, which makes the seamless handover from WiFi to cellular maybe less important than many would suggest.
VoWiFi is great for many home users because they can make good quality calls even in locations where cellular struggles to provide coverage, such as a basement. And when roaming, a user could make a VoWiFi call using hotel Wi-Fi access and pay the normal tariff.
Why QoS is vital
Now, what about the quality issue? This is more complex due to the technologies involved. There are three main concerns – that VoWiFi runs on unlicensed radio bands, that ISP networks may be involved and that these are outside the operator’s control, and that multiple applications using the Wi-Fi network may cause congestion.
Ensuring the Quality of Service (QoS) of operator-controlled VoWiFi is essential, and there are solid mechanisms to do so. The technicalities are detailed (in fact we’re writing a White Paper on the topic right now) but essentially boil down to prioritizing voice packets and traffic from the handset to the WiFi access, through the backbone and core networks – end-to-end.
So, the technology to deliver convenient, VoWiFi to subscribers is ready. Yet still, some people ask why operators would want to introduce VoWiFi? Well, the question really should be why not? As far as the operator is concerned, VoWiFi and VoLTE are two sides of the same coin, with the identical IMS core being used to support both. With VoWiFi offering new benefits to users such as better indoor coverage, which is the main driver along with cheaper roaming, there really is no question to answer.
Finally, it’s time for me to blow the Nokia trumpet a little. Nokia Networks has gained real-life experience of ensuring service parity between circuit-switched and data networks, including implementation of the world’s largest IMS LTE network supporting more than 50 million subscribers. We offer a robust, proven IMS solution that offers all the standard back-office functionality needed and we have the expertise to make it all work. And those satisfied VoLTE references that we have are ready to provide VoWiFi as well.
Read more about VoLTE here or this recent blog:
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