Almost all xmartO cameras with 2-way audio come with camera siren alarm. It's a feature based on the motion detection and the built-in speaker.

Here is how to enable the siren of a camera, 

1. Enable siren while the camera is working standalone via App. 

In App - go to camera's setting - Motion detection management, you can turn on the Motion detection siren. By default the siren is an alarm or a long beep. Tap 'customize' you can record your own alarm or voice message.

Unselect the 'Motion detection siren' will disable it.

2. Enable siren while the camera is working with NVR.

a) In NVR menu - system setting - CH setting - Video detection; see the options below. Check the IPC Siren/ Alarm will turn on the siren. The siren is not cutomizable when the cameras work with NVR. 

b) If you did not find IPC siren option in the video detection, your NVR version should be a bit old. Upgrade your NVR to latest verison should give you the option. Do the upgrade in System setting - System admin - system upgrade. 

If you have any question, please contact us via support@xmarto.com.