When I'm on call with a person, and someone else is calling me at the same time, why doesn't my iPhone notify me that someone is calling me now?
iPhone 8 Plus
The answer largely depends on your cellular carrier, and whether they use GSM (like AT&T in the U.S.) or CDMA (like Verizon in the U.S.).
Here is more information:
Call forwarding, call waiting, and other call features on iPhone - Apple Support
I'm in Australia, I think they use GSM network. Which setting do need to turn on/off to allow my iPhone to notify me when someone is calling me?
If you are on GSM, you should set:
Settings > Phone > Call Waiting = "on"
If you don't have such a setting, then you likely are not on GSM.
My call waiting setting is already on. Is this the only setting i need to set -ON? it seems like iPhone don't notify me even those it's already on?!
Yes, that should be all you need from Settings.
If you’re not being notified, you should check with your cellular carrier.
2 calls at the same time
