How to come true two way talk function on DMSS?

For two way talk function, you should confirm two devices both support pick up(Collect the audio signal) and speaker (send the audio signal). For example ,your camera has build in mac and speaker .and your NVR connects to the pick up and speaker also . you standing at the NVR side can talk with the person who is at camera side directly.If you add the camera to DMSS ,you can also come true the function ,if camera and mobile both support speaker and pick up. Note:On DMSS ,if you add NVR to DMSS, and you want to come true the two way talk between NVR and mobile side.In other word, the audio resource from NVR(NVR connect the pickup and speaker by audio in/out port ) . You should long press the speaker icon in DMSS. If you add camera to DMSS or audio resource from camera, you should short press the speaker icon in DMSS, also confirm the audio encoding is enabled. You can login the device webpage and enable the speark icon in preview to do the test .