diff --git a/browser/components/loop/MozLoopService.jsm b/browser/components/loop/MozLoopService.jsm
index a71195569e8..b0a0e13091a 100644
--- a/browser/components/loop/MozLoopService.jsm
+++ b/browser/components/loop/MozLoopService.jsm
@@ -365,7 +365,7 @@ let MozLoopServiceInternal = {
           }
         };
 
-        // Send job to worker to do saving to
+        // Send job to worker to do log sanitation, transcoding and saving to
         // disk for pickup by telemetry on next startup, which then uploads it.
 
         let worker = new ChromeWorker("MozLoopWorker.js");
diff --git a/browser/components/loop/MozLoopWorker.js b/browser/components/loop/MozLoopWorker.js
index 909ccad9f2d..309188cf66b 100644
--- a/browser/components/loop/MozLoopWorker.js
+++ b/browser/components/loop/MozLoopWorker.js
@@ -38,7 +38,13 @@ onmessage = function(e) {
   let filename = e.data.filename;
   let ping = e.data.ping;
 
-  let pingStr = JSON.stringify(ping);
+  // Anonymize data
+  resetIpMask();
+  ping.payload.localSdp = redactSdp(ping.payload.localSdp);
+  ping.payload.remoteSdp = redactSdp(ping.payload.remoteSdp);
+  ping.payload.log = sanitizeLogs(ping.payload.log);
+
+  let pingStr = anonymizeIPv4(sanitizeUrls(JSON.stringify(ping)));
 
   // Save to disk
   let array = Encoder.encode(pingStr);
@@ -52,3 +58,104 @@ onmessage = function(e) {
     postMessage({fail: File.Error.toMsg(ex)});
   }
 };
+
+/**
+ * Mask upper 24-bits of ip address with fake numbers. Call resetIpMask() first.
+ */
+
+let IpMap = {};
+let IpCount = 0;
+
+function resetIpMask() {
+  IpMap = {};
+  IpCount = Math.floor(Math.random() * 16777215) + 1;
+}
+
+/**
+ * Masks upper 24-bits of ip address with fake numbers. Grunt function.
+ *
+ * @param {DOMString} ip address
+ */
+function maskIp(ip) {
+  let isInvalidOrRfc1918or3927 = function(p1, p2, p3, p4) {
+    let invalid = octet => octet < 0 || octet > 255;
+    return invalid(p1) || invalid(p2) || invalid(p3) || invalid(p4) ||
+    (p1 == 10) ||
+    (p1 == 172 && p2 >= 16 && p2 <= 31) ||
+    (p1 == 192 && p2 == 168) ||
+    (p1 == 169 && p2 == 254);
+  };
+
+  let [p1, p2, p3, p4] = ip.split(".");
+
+  if (isInvalidOrRfc1918or3927(p1, p2, p3, p4)) {
+    return ip;
+  }
+  let key = [p1, p2, p3].join();
+  if (!IpMap[key]) {
+    do {
+      IpCount = (IpCount + 1049039) % 16777216; // + prime % 2^24
+      p1 = (IpCount >> 16) % 256;
+      p2 = (IpCount >> 8) % 256;
+      p3 = IpCount % 256;
+    } while (isInvalidOrRfc1918or3927(p1, p2, p3, p4));
+    IpMap[key] = p1 + "." + p2 + "." + p3;
+  }
+  return IpMap[key] + "." + p4;
+}
+
+/**
+ * Partially masks ip numbers in input text.
+ *
+ * @param {DOMString} text Input text containing IP numbers as words.
+ */
+function anonymizeIPv4(text) {
+  return text.replace(/\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b/g,
+                      maskIp.bind(this));
+}
+
+/**
+ * Sanitizes any urls of session information, like
+ *
+ *   - (id=31 url=https://call.services.mozilla.com/#call/ongoing/AQHYjqH_...)
+ *   + (id=31 url=https://call.services.mozilla.com/#call/xxxx)
+ *
+ *   - (id=35 url=about:loopconversation#incoming/1403134352854)
+ *   + (id=35 url=about:loopconversation#incoming/xxxx)
+ *
+ * @param {DOMString} text The text.
+ */
+function sanitizeUrls(text) {
+  let trimUrl = url => url.replace(/(#call|#incoming).*/g,
+                                   (match, type) => type + "/xxxx");
+  return text.replace(/\(id=(\d+) url=([^\)]+)\)/g,
+                      (match, id, url) =>
+                      "(id=" + id + " url=" + trimUrl(url) + ")");
+}
+
+/**
+ * Removes privacy sensitive information from SDP input text outright, like
+ *
+ *   a=fingerprint:sha-256 E9:DE:6A:FE:2A:2F:05: etc.
+ *   a=identity ...
+ *
+ * Redacts lines from match to EOL. Assumes \r\n\ linebreaks.
+ *
+ * @param {DOMString} sdp The sdp text.
+ */
+let redactSdp = sdp => sdp.replace(/\r\na=(fingerprint|identity):.*?\r\n/g,
+                                   "\r\n");
+
+/**
+ * Sanitizes log text of sensitive information, like
+ *
+ *   - srflx(IP4:192.168.1.3:60348/UDP|turn402-oak.tokbox.com:3478)
+ *   + srflx(IP4:192.168.1.3:60348/UDP|xxxx.xxx)
+ *
+ * @param {DOMString} log The log text.
+ */
+function sanitizeLogs(log) {
+  let rex = /(srflx|relay)\(IP4:\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}:\d{1,5}\/(UDP|TCP)\|[^\)]+\)/g;
+
+  return log.replace(rex, match => match.replace(/\|[^\)]+\)/, "|xxxx.xxx)"));
+}