1. Do not place the baby unit inside the crib, or in a position where the baby can grab it with their hands. On the other hand, the further you place it, the clarity of the sound decreases. Test and place the unit at the farthest point from the child, where the device can still pick up even the lowest sounds and transmit them clearly.
2. The baby should not have access to the connection/charging cables of the device. Make sure they cannot reach them.
3. Check if the parent unit is out of range, running out of battery, or in mute or low volume while you don't have it in your line of sight. Out of range or battery replacement/recharge notification functions, which many intercom systems have, are useful for this purpose.