Originally Posted by
javabytes
This isn’t really correct. I’ve had iMessage problems/annoyances when disabling the SIM. It goes without saying you wouldn’t receive any SMS messages sent to you by non-Apple users… but when disabling the SIM, it disables the line altogether on your phone and disassociates it from your iMessage numbers on your Apple account. You cannot send or receive iMessages over Wi-Fi or other data connection using your phone number if the SIM is disabled; even if the local SIM is providing a data connection, you are not able to use that to “retrieve” the messages for the number associated with the other SIM that you have disabled.
Physical SIMs were treated differently if you physically removed them vs. disabling; Apple (historically, though there have been reports of difficulty lately) gave a 30 day grace period during which time you could continue to keep using iMessage and FaceTime despite that number not being currently associated with the phone. Not so if you turn off the line in the iPhone settings (whether physical or eSIM).
That’s not been my experience using IMS on my iPhone with the data disabled on my domestic sim. I have walked streets in Europe and been able to make calls and receive messages using the disabled sim over IMS. Sounds like your iPhone isn’t configured properly or your provider doesn’t support WiFi calling and messaging.
My non cellular iPad is able to send and receive imessages using my cell number or my email. The same with FaceTime on the same iPad.
I said to disable the data for a sim. You said disable a sim which is completely different than what I said. My iPhone with data disabled receives messages from my work Android phone since I have WiFi enabled and my carrier supports service over WiFi.