diff --git a/gumble/gumble/udp15.go b/gumble/gumble/udp15.go
index 6919f35..fe8907c 100644
--- a/gumble/gumble/udp15.go
+++ b/gumble/gumble/udp15.go
@@ -559,27 +559,37 @@ func (c *Client) HandleUDPPacket15(packet []byte, pktNum uint64) {
 		log.Info("UDP15 #%d: ping response, ignoring", pktNum)
 		return
 	}
-	if msgType != 0x00 {
-		log.Warn("UDP15 #%d: unknown message type 0x%02x", pktNum, msgType)
+
+	// MumbleUDP.Audio protobuf format (1.5 native).
+	if msgType == 0x00 {
+		session, frameNum, opusData, terminator := decodeUDPAudio(plaintext)
+		c.dispatchOpus15(pktNum, session, int64(frameNum), opusData, terminator)
 		return
 	}
 
-	// Parse MumbleUDP.Audio protobuf.
-	session, frameNum, opusData, terminator := decodeUDPAudio(plaintext)
+	// Legacy UDPVoiceOpus format: type byte has bits 5-7 = 4.
+	if (msgType >> 5) == 4 {
+		c.handleLegacyUDPVoice(pktNum, plaintext)
+		return
+	}
 
+	log.Warn("UDP15 #%d: unknown message type 0x%02x", pktNum, msgType)
+}
+
+// dispatchOpus15 processes a decoded MumbleUDP.Audio frame and dispatches
+// the decoded PCM to audio listeners.
+func (c *Client) dispatchOpus15(pktNum uint64, session uint32, frameNum int64, opusData []byte, terminator bool) {
 	if len(opusData) == 0 && !terminator {
 		log.Info("UDP15 #%d: no opus data (session=%d frame=%d), skipping", pktNum, session, frameNum)
 		return
 	}
 
-	// Find the user.
 	user := c.Users[session]
 	if user == nil {
 		log.Warn("UDP15 #%d: unknown session %d", pktNum, session)
 		return
 	}
 
-	// Get or create decoder.
 	decoder := user.decoder
 	if decoder == nil {
 		codec := c.audioCodec
@@ -593,7 +603,6 @@ func (c *Client) HandleUDPPacket15(packet []byte, pktNum uint64) {
 	}
 
 	if terminator && len(opusData) == 0 {
-		// Decoder reset on terminator.
 		decoder.Reset()
 		log.Info("UDP15 #%d: terminator for %s, decoder reset", pktNum, user.Name)
 		return
@@ -603,9 +612,59 @@ func (c *Client) HandleUDPPacket15(packet []byte, pktNum uint64) {
 		return
 	}
 
-	// Detect sequence gaps via frame_number.
+	c.decodeAndDispatch(pktNum, user, decoder, frameNum, opusData)
+}
+
+// handleLegacyUDPVoice parses the legacy UDPVoice format (type byte 0x80)
+// inside a 1.5-decrypted payload.
+func (c *Client) handleLegacyUDPVoice(pktNum uint64, data []byte) {
+	pos := 0
+
+	// Session varint.
+	session, n := varint.Decode(data[pos:])
+	if n <= 0 {
+		log.Warn("UDP15 #%d: legacy session varint decode failed", pktNum)
+		return
+	}
+	pos += n
+
+	// Sequence varint.
+	seq, n := varint.Decode(data[pos:])
+	if n <= 0 {
+		log.Warn("UDP15 #%d: legacy seq varint decode failed", pktNum)
+		return
+	}
+	pos += n
+
+	// Length varint (bit 13 = terminator).
+	length, n := varint.Decode(data[pos:])
+	if n <= 0 {
+		log.Warn("UDP15 #%d: legacy length varint decode failed", pktNum)
+		return
+	}
+	pos += n
+
+	terminator := (length & 0x2000) != 0
+	audioLen := int(length &^ 0x2000)
+	if audioLen > len(data)-pos {
+		log.Warn("UDP15 #%d: legacy audio length %d > remaining %d",
+			pktNum, audioLen, len(data)-pos)
+		return
+	}
+
+	opusData := data[pos : pos+audioLen]
+
+	log.Info("UDP15 #%d: legacy voice session=%d seq=%d opus_len=%d term=%v",
+		pktNum, session, seq, len(opusData), terminator)
+
+	c.dispatchOpus15(pktNum, uint32(session), seq, opusData, terminator)
+}
+
+// decodeAndDispatch decodes an Opus frame and dispatches PCM to audio listeners.
+func (c *Client) decodeAndDispatch(pktNum uint64, user *User, decoder AudioDecoder, frameNum int64, opusData []byte) {
+	// Detect sequence gaps.
 	if user.audioSequenceValid {
-		gap := int64(frameNum) - user.audioSequence
+		gap := frameNum - user.audioSequence
 		if gap > 1 && gap < 100 {
 			log.Info("UDP15 #%d: seq gap for %s: %d -> %d (loss=%d), generating PLC",
 				pktNum, user.Name, user.audioSequence, frameNum, gap-1)
@@ -621,10 +680,9 @@ func (c *Client) HandleUDPPacket15(packet []byte, pktNum uint64) {
 			return
 		}
 	}
-	user.audioSequence = int64(frameNum)
+	user.audioSequence = frameNum
 	user.audioSequenceValid = true
 
-	// Decode Opus.
 	pcm, err := decoder.Decode(opusData, AudioMaximumFrameSize)
 	if err != nil {
 		log.Warn("UDP15 #%d: Opus decode failed for %s: %v", pktNum, user.Name, err)
@@ -634,12 +692,11 @@ func (c *Client) HandleUDPPacket15(packet []byte, pktNum uint64) {
 
 	log.Info("UDP15 #%d: Opus OK for %s, pcm_samples=%d", pktNum, user.Name, len(pcm))
 
-	// Dispatch.
 	event := AudioPacket{
 		Client:      c,
 		Sender:      user,
 		Target:      &VoiceTarget{ID: 0},
-		Sequence:    int64(frameNum),
+		Sequence:    frameNum,
 		AudioBuffer: AudioBuffer(pcm),
 	}
 	c.dispatchAudio(user, &event)