diff --git a/audio/call-in.m4a b/audio/call-in.m4a
new file mode 100644
index 00000000..71ca0f45
Binary files /dev/null and b/audio/call-in.m4a differ
diff --git a/audio/call-in.mp3 b/audio/call-in.mp3
deleted file mode 100644
index b42cbe48..00000000
Binary files a/audio/call-in.mp3 and /dev/null differ
diff --git a/audio/call-out.m4a b/audio/call-out.m4a
new file mode 100644
index 00000000..089050fb
Binary files /dev/null and b/audio/call-out.m4a differ
diff --git a/audio/msg.m4a b/audio/msg.m4a
new file mode 100644
index 00000000..372143dc
Binary files /dev/null and b/audio/msg.m4a differ
diff --git a/audio/msg.mp3 b/audio/msg.mp3
deleted file mode 100644
index bf53313a..00000000
Binary files a/audio/msg.mp3 and /dev/null differ
diff --git a/package.json b/package.json
index 874505ce..238d0803 100644
--- a/package.json
+++ b/package.json
@@ -26,7 +26,7 @@
     "umd/index.dev.js.map",
     "umd/tinode.prod.js",
     "umd/tinode.dev.js",
-    "audio/*.mp3",
+    "audio/*.m4a",
     "css/base.css",
     "css/base.min.css",
     "img/*.png",
diff --git a/src/views/incoming-call-view.jsx b/src/views/incoming-call-view.jsx
index fd5e7744..b629826c 100644
--- a/src/views/incoming-call-view.jsx
+++ b/src/views/incoming-call-view.jsx
@@ -12,7 +12,7 @@ import { CALL_STATE_INCOMING_RECEIVED } from '../constants.js';
 import { makeImageUrl } from '../lib/blob-helpers.js';
 import { clipStr } from '../lib/utils.js'
 
-const RING_SOUND = new Audio('audio/call-in.mp3');
+const RING_SOUND = new Audio('audio/call-in.m4a');
 
 export default class IncomingCallView extends React.Component {
   constructor(props) {
diff --git a/src/views/tinode-web.jsx b/src/views/tinode-web.jsx
index 06a2c622..6ea7fa89 100644
--- a/src/views/tinode-web.jsx
+++ b/src/views/tinode-web.jsx
@@ -31,7 +31,7 @@ import { secondsToTime } from '../lib/strformat.js'
 import { updateFavicon } from '../lib/utils.js';
 
 // Sound to play on message received.
-const POP_SOUND = new Audio('audio/msg.mp3');
+const POP_SOUND = new Audio('audio/msg.m4a');
 
 const messages = defineMessages({
   reconnect_countdown: {
diff --git a/src/widgets/call-panel.jsx b/src/widgets/call-panel.jsx
index 2e9e6b21..543a7a93 100644
--- a/src/widgets/call-panel.jsx
+++ b/src/widgets/call-panel.jsx
@@ -9,6 +9,9 @@ import { CALL_STATE_OUTGOING_INITATED, CALL_STATE_IN_PROGRESS } from '../constan
 
 import { clipStr } from '../lib/utils.js'
 
+const RING_SOUND = new Audio('audio/call-out.m4a');
+RING_SOUND.loop = true;
+
 const messages = defineMessages({
   already_in_call: {
     id: 'already_in_call',
@@ -133,6 +136,9 @@ class CallPanel extends React.PureComponent {
       .then(stream => {
         this.setState({localStream: stream});
         this.localRef.current.srcObject = stream;
+
+        RING_SOUND.play();
+
         // Send call invitation.
         this.props.onInvite(this.props.topic, this.props.seq, this.props.callState);
       })
@@ -140,6 +146,9 @@ class CallPanel extends React.PureComponent {
   }
 
   stop() {
+    RING_SOUND.stop();
+    RING_SOUND.currentTime = 0;
+
     this.stopTracks(this.localRef.current);
     this.stopTracks(this.remoteRef.current);
     if (this.state.pc) {