I attempted to contact MTN to activate WiFi calling on their network. However, the process involved being transferred to multiple call agents, which took around 20 minutes. Eventually, I was asked to test WiFi calling by making a call with airplane mode and WiFi enabled. Unfortunately, this attempt proved unsuccessful, as a prompt indicated that airplane mode needed to be deactivated to place the call. It's possible that this issue is related to my current ISP, a smaller company called Ballito ISP Who may not be on the whitelist. However, I also observed that WiFi calling did not work on my friend's Vodacom fiber network either.
The reason I must stick with MTN is that they provide the best signal in my area. If I switch to another network, I may risk being left without a connection during times when WiFi is down.
When my current fiber contract ends, I suppose I could consider switching to Afrihost. However, doing so would require signing another contract and dealing with the hassle of releasing the fiber line, among other things.