The Avaya 4602 SW IP Phone (Model 4602D02A) with 2.2.2 and earlier SIP firmware uses a constant media port number for calls, which allows remote attackers to cause a denial of service (audio quality loss) via a flood of packets to the RTP port.
https://exchange.xforce.ibmcloud.com/vulnerabilities/34968
http://www.sipera.com/index.php?action=resources%2Cthreat_advisory&tid=302&
http://support.avaya.com/elmodocs2/security/ASA-2007-263.htm