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diff --git a/third_party/libwebrtc/api/voip/voip_dtmf.h b/third_party/libwebrtc/api/voip/voip_dtmf.h
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+++ b/third_party/libwebrtc/api/voip/voip_dtmf.h
@@ -0,0 +1,74 @@
+/*
+ *  Copyright (c) 2020 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_VOIP_VOIP_DTMF_H_
+#define API_VOIP_VOIP_DTMF_H_
+
+#include "api/voip/voip_base.h"
+
+namespace webrtc {
+
+// DTMF events and their event codes as defined in
+// https://tools.ietf.org/html/rfc4733#section-7
+enum class DtmfEvent : uint8_t {
+  kDigitZero = 0,
+  kDigitOne,
+  kDigitTwo,
+  kDigitThree,
+  kDigitFour,
+  kDigitFive,
+  kDigitSix,
+  kDigitSeven,
+  kDigitEight,
+  kDigitNine,
+  kAsterisk,
+  kHash,
+  kLetterA,
+  kLetterB,
+  kLetterC,
+  kLetterD
+};
+
+// VoipDtmf interface provides DTMF related interfaces such
+// as sending DTMF events to the remote endpoint.
+class VoipDtmf {
+ public:
+  // Register the payload type and sample rate for DTMF (RFC 4733) payload.
+  // Must be called exactly once prior to calling SendDtmfEvent after payload
+  // type has been negotiated with remote.
+  // Returns following VoipResult;
+  //  kOk - telephone event type is registered as provided.
+  //  kInvalidArgument - `channel_id` is invalid.
+  virtual VoipResult RegisterTelephoneEventType(ChannelId channel_id,
+                                                int rtp_payload_type,
+                                                int sample_rate_hz) = 0;
+
+  // Send DTMF named event as specified by
+  // https://tools.ietf.org/html/rfc4733#section-3.2
+  // `duration_ms` specifies the duration of DTMF packets that will be emitted
+  // in place of real RTP packets instead.
+  // Must be called after RegisterTelephoneEventType and VoipBase::StartSend
+  // have been called.
+  // Returns following VoipResult;
+  //  kOk - requested DTMF event is successfully scheduled.
+  //  kInvalidArgument - `channel_id` is invalid.
+  //  kFailedPrecondition - Missing prerequisite on RegisterTelephoneEventType
+  //   or sending state.
+  virtual VoipResult SendDtmfEvent(ChannelId channel_id,
+                                   DtmfEvent dtmf_event,
+                                   int duration_ms) = 0;
+
+ protected:
+  virtual ~VoipDtmf() = default;
+};
+
+}  // namespace webrtc
+
+#endif  // API_VOIP_VOIP_DTMF_H_