diff --git a/step-05/js/main.js b/step-05/js/main.js
index 51b3fa3..8c60d51 100644
--- a/step-05/js/main.js
+++ b/step-05/js/main.js
@@ -190,8 +190,6 @@ function doAnswer() {
 }
 
 function setLocalAndSendMessage(sessionDescription) {
-  // Set Opus as the preferred codec in SDP if Opus is present.
-  //  sessionDescription.sdp = preferOpus(sessionDescription.sdp);
   pc.setLocalDescription(sessionDescription);
   console.log('setLocalAndSendMessage sending message', sessionDescription);
   sendMessage(sessionDescription);
@@ -257,81 +255,3 @@ function stop() {
   pc.close();
   pc = null;
 }
-
-///////////////////////////////////////////
-
-// Set Opus as the default audio codec if it's present.
-function preferOpus(sdp) {
-  var sdpLines = sdp.split('\r\n');
-  var mLineIndex;
-  // Search for m line.
-  for (var i = 0; i < sdpLines.length; i++) {
-    if (sdpLines[i].search('m=audio') !== -1) {
-      mLineIndex = i;
-      break;
-    }
-  }
-  if (mLineIndex === null) {
-    return sdp;
-  }
-
-  // If Opus is available, set it as the default in m line.
-  for (i = 0; i < sdpLines.length; i++) {
-    if (sdpLines[i].search('opus/48000') !== -1) {
-      var opusPayload = extractSdp(sdpLines[i], /:(\d+) opus\/48000/i);
-      if (opusPayload) {
-        sdpLines[mLineIndex] = setDefaultCodec(sdpLines[mLineIndex],
-          opusPayload);
-      }
-      break;
-    }
-  }
-
-  // Remove CN in m line and sdp.
-  sdpLines = removeCN(sdpLines, mLineIndex);
-
-  sdp = sdpLines.join('\r\n');
-  return sdp;
-}
-
-function extractSdp(sdpLine, pattern) {
-  var result = sdpLine.match(pattern);
-  return result && result.length === 2 ? result[1] : null;
-}
-
-// Set the selected codec to the first in m line.
-function setDefaultCodec(mLine, payload) {
-  var elements = mLine.split(' ');
-  var newLine = [];
-  var index = 0;
-  for (var i = 0; i < elements.length; i++) {
-    if (index === 3) { // Format of media starts from the fourth.
-      newLine[index++] = payload; // Put target payload to the first.
-    }
-    if (elements[i] !== payload) {
-      newLine[index++] = elements[i];
-    }
-  }
-  return newLine.join(' ');
-}
-
-// Strip CN from sdp before CN constraints is ready.
-function removeCN(sdpLines, mLineIndex) {
-  var mLineElements = sdpLines[mLineIndex].split(' ');
-  // Scan from end for the convenience of removing an item.
-  for (var i = sdpLines.length - 1; i >= 0; i--) {
-    var payload = extractSdp(sdpLines[i], /a=rtpmap:(\d+) CN\/\d+/i);
-    if (payload) {
-      var cnPos = mLineElements.indexOf(payload);
-      if (cnPos !== -1) {
-        // Remove CN payload from m line.
-        mLineElements.splice(cnPos, 1);
-      }
-      // Remove CN line in sdp
-      sdpLines.splice(i, 1);
-    }
-  }
-
-  sdpLines[mLineIndex] = mLineElements.join(' ');
-  return sdpLines;
-}