If your new iPhone 15 is not allowing notifications from the DMSS app when lines are tripped, follow these steps to troubleshoot and resolve the issue:

Ensure that the DMSS App is Updated

1. Check for Updates:
- Open the App Store on your iPhone.
- Tap on your profile picture at the top right corner.
- Scroll to find the DMSS app and see if an update is available. If it is, tap on "Update."

Verify Notification Settings on iPhone

2. Access Settings:
- Open the "Settings" app on your iPhone.

3. Navigate to Notifications:
- Scroll down and tap on "Notifications."

4. Select DMSS:
- Find and select the DMSS app from the list of applications.

5. Enable Notifications:
- Ensure that "Allow Notifications" is toggled on.
- Check that the alerts are set to show in the Notification Center, on the Lock Screen, and as Banners.

Check In-app Notification Settings

6. Open DMSS App:
- Launch the DMSS app on your iPhone.

7. Go to Device Settings:
- Tap on "Device Details" or the relevant section for your specific security device.

8. Multi-channel Alarm Subscription:
- Look for the option labeled "Multi-channel Alarm Subscription." Ensure that this is enabled to receive notifications for events like line trips - learn more.

Confirm Network Settings

9. Verify Internet Connection:
- Ensure your device is connected to the internet (Wi-Fi or cellular data).

10. Check Firewall or Security Settings:
- If you're using a network with restricted access, ensure that your firewall or security settings permit notifications from the DMSS app.

Restart Your Phone

11. Perform a Restart:
- Press and hold the side button until the power off slider appears.
- Slide to power off, then turn your iPhone back on after a few seconds.

Reinstall the DMSS App

12. Delete and Reinstall:
- If notifications are still not working, consider deleting the DMSS app and reinstalling it from the App Store.

13. Set Up Notifications Again:
- After reinstalling, repeat the notification settings process to ensure they are configured properly.

Check Alternatives and Support Forums

14. Visit Community Forums:
- If the issue persists, checking community forums like IP Cam Talk and Reddit can provide insights from users who faced similar issues - learn more - learn more.

By following these steps, you should be able to resolve the issue of not receiving notifications from the DMSS app on your iPhone 15. If problems continue, consider reaching out to DMSS support for further assistance.