diff --git a/pc/channel.cc b/pc/channel.cc
index ea4684f4f5..9156f21f66 100644
--- a/pc/channel.cc
+++ b/pc/channel.cc
@@ -1077,6 +1077,9 @@ void BaseChannel::CacheRtpAbsSendTimeHeaderExtension_n(
   if (sdes_transport_) {
     sdes_transport_->CacheRtpAbsSendTimeHeaderExtension(
         rtp_abs_sendtime_extn_id);
+  } else if (dtls_srtp_transport_) {
+    dtls_srtp_transport_->CacheRtpAbsSendTimeHeaderExtension(
+        rtp_abs_sendtime_extn_id);
   } else {
     RTC_LOG(LS_WARNING)
         << "Trying to cache the Absolute Send Time extension id "
diff --git a/pc/dtlssrtptransport.h b/pc/dtlssrtptransport.h
index e03342597e..55b96c1645 100644
--- a/pc/dtlssrtptransport.h
+++ b/pc/dtlssrtptransport.h
@@ -46,6 +46,13 @@ class DtlsSrtpTransport : public RtpTransportInternalAdapter {
 
   bool IsActive() { return srtp_transport_->IsActive(); }
 
+  // Cache RTP Absoulute SendTime extension header ID. This is only used when
+  // external authentication is enabled.
+  void CacheRtpAbsSendTimeHeaderExtension(int rtp_abs_sendtime_extn_id) {
+    srtp_transport_->CacheRtpAbsSendTimeHeaderExtension(
+        rtp_abs_sendtime_extn_id);
+  }
+
   // TODO(zhihuang): Remove this when we remove RtpTransportAdapter.
   RtpTransportAdapter* GetInternal() override { return nullptr; }
 
diff --git a/pc/srtptransport.h b/pc/srtptransport.h
index 23e2a3c544..d098cd8317 100644
--- a/pc/srtptransport.h
+++ b/pc/srtptransport.h
@@ -93,8 +93,8 @@ class SrtpTransport : public RtpTransportInternalAdapter {
   // Returns rtp auth params from srtp context.
   bool GetRtpAuthParams(uint8_t** key, int* key_len, int* tag_len);
 
-  // Helper method to get RTP Absoulute SendTime extension header id if
-  // present in remote supported extensions list.
+  // Cache RTP Absoulute SendTime extension header ID. This is only used when
+  // external authentication is enabled.
   void CacheRtpAbsSendTimeHeaderExtension(int rtp_abs_sendtime_extn_id) {
     rtp_abs_sendtime_extn_id_ = rtp_abs_sendtime_extn_id;
   }