diff --git a/app.js b/app.js
index 7140d82..7d34e75 100644
--- a/app.js
+++ b/app.js
@@ -101,7 +101,7 @@ const mediaCodecs = [
 
 const getRtpCapabilities = (callId, callback) => {
   console.log('[getRtpCapabilities] callId', callId);
-  const rtpCapabilities = videoCalls[callId].router.rtpCapabilities;
+  const rtpCapabilities = videoCalls[callId] = { router: rtpCapabilities };
   callback({ rtpCapabilities });
 }