I am using the answer in this topic. iPhone - how to determine carrier of the device (AT&T, Verizon, etc?) which is the same as getting operator details in iphone. Although it works fine when using a sim card, the returned carrier name if there is no SIM card is the old carrier name. It doesn't detect that the SIM is removed.
I know this contradicts with Apple documentation that if there is no carrier, CTCarrier object shall be nil. But in my app I logged the carrier info and it gives me the latest carrier name although no sim is installed.
According to the documentation for
If you configure a device for a carrier and then remove the SIM card, this property retains the name of the carrier.
As far as I know, you cannot detect if the SIM card is installed. You can only determine if a WWAN connection is available using