Wi-Fi calling on Cell C is set to launch on 1 October, with support for the feature coming first to the AG Style handset.
It will let Cell C subscribers make and receive calls, and send and receive SMS messages, over any Wi-Fi network they are connected to.
In addition to effectively extending Cell C coverage to wherever you have Wi-Fi access, which could help international travellers reduce their roaming bills, the operator has also launched two deals specific to Wi-Fi calling.
These offer 1,000 Cell C on-network minutes, 1,000 SMS messages, and 500 all-network minutes for R199 per month.
To get an idea of what subscribers can expect from Cell C Wi-Fi calling, we put the service to the test using a ZTE Blade V6 which is set to become available on Cell C from 15 October.
Disconnection from the Cell C mobile network
Two things immediately stood out while testing Cell C’s Wi-Fi calling service on our Android device.
Firstly, there was an additional icon in the notification tray which appeared when connected to a Wi-Fi network – it showed whether Wi-Fi calling was available or not.
Secondly, when Wi-Fi calling was available, the phone would disconnect from Cell C’s mobile network.
This could be a smart long-term move from the operator, as it may free up capacity on its towers for those without Wi-Fi calling or who are not on Wi-Fi.
We tested Wi-Fi calling on a number of different Wi-Fi networks which were connected to the Internet through various carriers and service providers.
On DSL accounts from Vox and Webafrica, we were unable to connect to the Cell C Wi-Fi calling service – receiving messages such as “Error5:DNS Error”.
On Telkom LTE-A and a Centurion-based wireless ISP (Level-7), we were able to access Wi-Fi calling.
Cell C is aware of the DNS error experienced on some DSL networks.
Making and receiving calls
We also tested whether you could make and receive calls to or from Cell C, MTN, Telkom, and Vodacom, while on Cell C Wi-Fi calling.
All calls made from our Cell C number routed correctly.
Calls made from other mobile operators came through to our device on Wi-Fi calling, with the exception of those placed from a Telkom number that had been ported from Vodacom.
Calls from this Telkom number did not come through whether we were on Wi-Fi calling or Cell C’s mobile network.
We were able to call this ported Telkom number from our Cell C test SIM. Calls from an unported Telkom number connected successfully.
Cell C is aware of this routing issue between a number ported to Telkom and one of its SIMs.
While testing call routing, two things stood out:
- The icon on the green call button in the dialler changed to show that a Wi-Fi call was being made.
- When hanging up from the device on Cell C Wi-Fi calling, it took a few seconds for the network to register that the call had been disconnected. If the other phone was ringing, it continued to ring for a few seconds while the call disconnected.
Call quality was tested with a Telkom mobile subscriber, while the ZTE Blade V6 was connected to a hotspot backed by a Telkom LTE-A wireless broadband connection.
Both participants could hear one another clearly, and there was no discernible latency between speaking and getting a reply.
Update: Cell C said it has isolated the DNS problems we reported to likely be due to a query standard not supported by our DSL router. It has addressed the issue by building a fallback to a supported DNS query into devices that support Wi-Fi calling.
Disclaimer: Cell C provided a ZTE Blade V6 and a SIM with R100 airtime with which to test its Wi-Fi calling service.