First, the Audio function must be activated in the camera
1. Configuration
2. Video / Audio
3. Enable the function
In the SL (Sound & Light) cameras audio and speaker must be set to auto or talkback, otherwise only the configured warning can be played.
1. Audio Output (Talkback / Warning / Auto)
2. Speaker (Talkback / Warning / Auto)
If the camera is added via IP the two-way audio can be used by pressing and holding the mic button.
If the camera is added via the recorder to the App, the two-way audio can be used by taping once on the image and the click on the symbol, which will show up at the top.
Then press and hold the Mic button to speak.
More FAQ about the audio configuration
Safire Smart - Audio recording configuration – Visiotech (visiotechsecurity.com)
Safire Smart - Upload custom audio files to Safire Smart camera – Visiotech (visiotechsecurity.com)