diff --git a/app/composables/useAudioRecorder.ts b/app/composables/useAudioRecorder.ts
index 0b2f5e1..8359273 100644
--- a/app/composables/useAudioRecorder.ts
+++ b/app/composables/useAudioRecorder.ts
@@ -36,22 +36,25 @@ export function useAudioRecorder() {
   })
 
   // Get preferred MIME type for recording
+  // Prefer ogg/opus as it's required by WhatsApp for voice notes
   const getMimeType = (): string => {
     const types = [
+      'audio/ogg;codecs=opus',  // Preferred for WhatsApp PTT
+      'audio/ogg',
       'audio/webm;codecs=opus',
       'audio/webm',
-      'audio/ogg;codecs=opus',
-      'audio/ogg',
       'audio/mp4',
       'audio/mpeg'
     ]
 
     for (const type of types) {
       if (MediaRecorder.isTypeSupported(type)) {
+        console.log('[AudioRecorder] Using MIME type:', type)
         return type
       }
     }
 
+    console.warn('[AudioRecorder] No preferred type supported, using webm fallback')
     return 'audio/webm' // fallback
   }
 
diff --git a/server/api/messages/[instanceId]/[chatId]/send.post.ts b/server/api/messages/[instanceId]/[chatId]/send.post.ts
index 8d63f72..9e0cf99 100644
--- a/server/api/messages/[instanceId]/[chatId]/send.post.ts
+++ b/server/api/messages/[instanceId]/[chatId]/send.post.ts
@@ -274,10 +274,19 @@ async function handleMediaMessage(
             mimetype: file.type
           } as AnyMediaMessageContent
         } else if (mediaType === 'audio') {
+          // For PTT (voice notes), WhatsApp requires audio/ogg; codecs=opus
+          // If the browser sends webm, we force the mimetype to ogg
+          // The opus codec is the same, just different container
+          let audioMimetype = file.type
+          if (isPtt && file.type.includes('webm')) {
+            audioMimetype = 'audio/ogg; codecs=opus'
+            console.log(`[Send] Converting PTT mimetype from ${file.type} to ${audioMimetype}`)
+          }
+
           content = {
             audio: file.data,
             ptt: isPtt,
-            mimetype: file.type
+            mimetype: audioMimetype
           } as AnyMediaMessageContent
         } else {
           // Document