woops need this too

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@13407 d0543943-73ff-0310-b7d9-9358b9ac24b2

conf/autoload_configs/switch.conf.xml

@@ -60,6 +60,7 @@
     <!--RTP port range -->
     <!--<param name="rtp-start-port" value="16384"/>-->
     <!--<param name="rtp-end-port" value="32768"/>-->
+    <param name="rtp-enable-zrtp" value="true"/>
   </settings>
 
 </configuration>