The eSIM from Revolut does data only as far as I know so you'll need to ensure that you set your iPhone to use it for mobile data while in South Africa.I don't think 48 has any roaming agreements in South Africa so you wouldn't be able to make/receiv...
What OS version are you running?Do you have a sim card from another network you could try in the phone to see if its phone or sim related.What happens if you enable WiFi Tethering?
