Fixes issue 1712.
Thanks to Joachim for the patch !
BTW,also fixes invalid missed call notification when call is declined.

git-svn-id: http://csipsimple.googlecode.com/svn/trunk/CSipSimple@2268 9f815046-5998-e9c0-b7e2-ac03a23edfa4
Fixes issue 2378.
Integrate zrtp4pj fix to have it safe to pmedia multithreading.

git-svn-id: http://csipsimple.googlecode.com/svn/trunk/CSipSimple@2269 9f815046-5998-e9c0-b7e2-ac03a23edfa4