Ugh! I've had that issue with Telkom mobile. Use a variety of tricks include activating international roaming for sms, loading small amounts of whatever data service's they offer, etc
Never quite figured out what combo worked when it eventually started working.
Thanks. I think I’ve tried pretty much everything with no joy. I read my MTN eSim may be to blame. Considering removing plan but then I have to go In store and do a physical sim swap to get a new QR code to reload the plan. Between Apple & the networks they don’t make it easy!

