Is Wi-Fi Calling an alternative to in-building cellular solutions?
Wi-Fi Calling is a feature supported in newer smartphones, enabling calls and SMS over Wi-Fi as an alternative to cellular. Although Voice over Wi-Fi (VoWi-Fi) has been available for some time via apps such as Skype, Facetime and WhatsApp, these apps are not integrated with the smartphone’s native “green button”.
Wi-Fi Calling, on the other hand is designed to give a better user experience than the existing 3rd party apps, and is offered by all four UK mobile network operators. The solutions vary however between operators and are not provided by many of the virtual operators. EE and Vodafone’s service works seamlessly with the green button once the phone is set up correctly, but Vodafone users need the right type of phone, bought from Vodafone, with the right type of contract. O2 and Three require a smartphone app: TU Go and InTouch respectively. In all cases it isn’t possible to roam between Wi-Fi and cellular networks during a call.
Wi-Fi Calling can be a great solution where the cellular coverage is poor, such as inside some homes and buildings. However, there are still a number of drawbacks which mean it can’t provide the same service quality as cellular in-building solutions:
- Wi-Fi Calling is not available to all users. That might not be a problem in the home, but would be an issue in a building where staff and visitors use a variety of different mobile providers, contracts and phone types.
- Wi-Fi Calling requires some smartphone setup or an app. The apps are not universal on all smartphones: O2’s TU Go and Three’s InTouch apps have 1-5M and 0.5-1M Android installs respectively, which still leaves a significant number of phones without the required app.
- Cellular has better security, mobility and voice quality than Wi-Fi.
- Wi-Fi call quality would also be affected by contention with heavy Wi-Fi data usage.
- There is no roaming between Wi-Fi and cellular or between separate Wi-Fi networks, so calls drop if users move out of Wi-Fi range.
- Wi-Fi propagation inside buildings is poorer than cellular due to much higher frequencies (5 GHz for Wi-Fi compared to 0.8-2.6 GHz for cellular), often leading to Wi-Fi coverage holes.
- In-building cellular provides resilience in case of Wi-Fi failure.
Further development of Wi-Fi Calling (VoWi-Fi) has largely stopped as operators turn their attention to other technologies such as Voice over LTE (VoLTE). Indeed Virgin Media shut down its own Wi-Fi Calling service in April 2016. Meanwhile, DAS and small cell vendors continue to develop their in-building cellular products. So although Wi-Fi calling is popular in some homes, it’s unlikely to reduce the need for cellular coverage inside larger buildings.
Mike Kennett, Wireless Consultant