I also developed an application that listens to SMS. I did a lot of research but I couldn't solve this with Flutter. And I did it with Kotlin. If the application is going to be open all the time, you need to get permission from the user to ignore battery optimization. Don't forget to get permission for SMS too. (These may be sensitive permissions) If you want to review it, you can look here ->> https://github.com/dcicek/read_sms