diff --git a/src/devices/cloud_iii_s_wireless.rs b/src/devices/cloud_iii_s_wireless.rs
index 71f1bde..4400957 100644
--- a/src/devices/cloud_iii_s_wireless.rs
+++ b/src/devices/cloud_iii_s_wireless.rs
@@ -52,6 +52,7 @@ const COLOR_COMMAND_ID: u8 = 0x4D;
 const CHARGE_STATE_COMMAND_ID: u8 = 0x48;
 const GET_MIC_MUTE_COMMAND_ID: u8 = 0x04;
 const GET_SIDE_TONE_COMMAND_ID: u8 = 0x16;
+const SET_SIDE_TONE_COMMAND_ID: u8 = 0x0D;
 const GET_AUTO_POWER_OFF_COMMAND_ID: u8 = 0x4B;
 const GET_VOICE_PROMPT_COMMAND_ID: u8 = 0x14;
 
@@ -210,8 +211,14 @@ impl Device for CloudIIISWireless {
         Some(packet)
     }
 
-    fn set_side_tone_packet(&self, _side_tone_on: bool) -> Option<Vec<u8>> {
-        None
+    fn set_side_tone_packet(&self, side_tone_on: bool) -> Option<Vec<u8>> {
+        // Confirmed via NGenuity USB capture: `0c 02 03 00 00 0d <0|1>`.
+        // byte[3] = 0x00 marks a SET (vs 0x01 for GET).
+        let mut packet = BASE_PACKET.to_vec();
+        packet[3] = 0x00;
+        packet[5] = SET_SIDE_TONE_COMMAND_ID;
+        packet[6] = side_tone_on as u8;
+        Some(packet)
     }
 
     fn get_side_tone_volume_packet(&self) -> Option<Vec<u8>> {