Cell C’s Wi-Fi calling service is now available on the iPhone 5C, 5S, 6, 6 Plus, 6S, 6S Plus, and SE.
To use the feature, devices must be updated to the latest version of Apple’s mobile operating system, iOS 9.3.2.
Carrier settings will update for customers over the course of the next few days, said Cell C.
If you want to do this immediately and have iOS 9.3.2, you can go to Settings > General > About and follow the prompts to complete the update.
Wi-Fi Calling can be turned on and off in Settings > Phone > Wi-Fi calling.
Cell C launched Wi-Fi Calling on 1 October 2015, letting subscribers turn any Wi-Fi hotspot into a Cell C base station to make calls, send SMS messages, buy bundles, and check voicemails and balances.
The service also lets international travellers pay local rates for calls, provided they are connected to a Wi-Fi hotspot.