diff --git a/src/webrtc/call.ts b/src/webrtc/call.ts
index 2d29a6c8d..35a7cb970 100644
--- a/src/webrtc/call.ts
+++ b/src/webrtc/call.ts
@@ -127,6 +127,8 @@ export enum CallEvent {
     FeedsChanged = 'feeds_changed',
 
     AssertedIdentityChanged = 'asserted_identity_changed',
+
+    LengthChanged = 'length_changed'
 }
 
 export enum CallErrorCode {
@@ -323,6 +325,9 @@ export class MatrixCall extends EventEmitter {
 
     private remoteSDPStreamMetadata: SDPStreamMetadata;
 
+    private callLengthInterval: number;
+    private callLength = 0;
+
     constructor(opts: CallOpts) {
         super();
         this.roomId = opts.roomId;
@@ -1479,6 +1484,10 @@ export class MatrixCall extends EventEmitter {
         // chrome doesn't implement any of the 'onstarted' events yet
         if (this.peerConn.iceConnectionState == 'connected') {
             this.setState(CallState.Connected);
+            this.callLengthInterval = setInterval(() => {
+                this.callLength++;
+                this.emit(CallEvent.LengthChanged, this.callLength);
+            }, 1000);
         } else if (this.peerConn.iceConnectionState == 'failed') {
             this.hangup(CallErrorCode.IceFailed, false);
         }
@@ -1729,6 +1738,10 @@ export class MatrixCall extends EventEmitter {
             clearTimeout(this.inviteTimeout);
             this.inviteTimeout = null;
         }
+        if (this.callLengthInterval) {
+            clearInterval(this.callLengthInterval);
+            this.callLengthInterval = null;
+        }
 
         // Order is important here: first we stopAllMedia() and only then we can deleteAllFeeds()
         // We don't stop media if the call was replaced as we want to re-use streams in the successor