diff --git a/src/UA.js b/src/UA.js
index 328b85622..692083498 100644
--- a/src/UA.js
+++ b/src/UA.js
@@ -719,7 +719,7 @@ JsSIP.UA.prototype.loadConfig = function(configuration) {
 
   // Via Host
   if (settings.hack_ip_in_contact) {
-    settings.via_host = JsSIP.Utils.getRandomIP();
+    settings.via_host = JsSIP.Utils.getRandomTestNetIP();
   }
 
   // Transports
diff --git a/src/Utils.js b/src/Utils.js
index 42db154e6..ef117bf62 100644
--- a/src/Utils.js
+++ b/src/Utils.js
@@ -137,11 +137,15 @@ JsSIP.Utils= {
     return JsSIP.C.causes.SIP_FAILURE_CODE;
   },
 
-  getRandomIP: function() {
-    function get_octet() {
-      return (Math.random() * 255 | 0) + 1;
+  /**
+  * Generate a random Test-Net IP (http://tools.ietf.org/html/rfc5735)
+  * @private
+  */
+  getRandomTestNetIP: function() {
+    function getOctet(from,to) {
+      return window.Math.floor(window.Math.random()*(to-from+1)+from);
     }
-    return get_octet()+'.'+get_octet()+'.'+get_octet()+'.'+get_octet();
+    return '192.0.2.' + getOctet(1, 254);
   },
 
   checkUAStatus: function(ua) {