Argus, Argus 2 and Argus Pro
Step 1. Open Reolink APP and connect to your camera.
Step 2. Click live view screen and you will see the screen like below.
Step 3. Click the small bell in the red pane on the right top.
Step 4. It will pop out the screen like below.
Step 5. Click the bell in the middle of the screen.
Now, it will trigger the siren.