iMessage is not working after SIM swap from one network to another
why Can’t I use my iMessage again after the sim swapping from another network to another
[Edited by Moderator]
iPhone 11, iOS 18
Question marked as
Did you already force restart your iPhone after changing the carrier?
Force restart iPhone - Apple Support
Also check the settings for messages on your iPhone, to make sure, that iMessage is enabled and in "Send & Receive" the correct phone number and email address is selected.
And the carrier settings should also checked for updates:
Manually update your carrier settings on your iPhone or iPad - Apple Support