1) Confirm that the APP microphone permission has been turned on
  2) Try to use other mobile phone talkback
  3) Try to connect in AP hotspot mode, if there is a sound during intercom in AP hotspot mode, it is generally a network problem, please check the router network connection
  4) If there is no sound during intercom in AP hotspot mode, the speaker of the device may be damaged, please contact the seller for after-sales service