The IAX2 protocol implementation in Asterisk Open Source 1.2.x before 1.2.35, 1.4.x before 1.4.26.2, 1.6.0.x before 1.6.0.15, and 1.6.1.x before 1.6.1.6; Business Edition B.x.x before B.2.5.10, C.2.x before C.2.4.3, and C.3.x before C.3.1.1; and s800i 1.3.x before 1.3.0.3 allows remote attackers to cause a denial of service (call-number exhaustion) by initiating many IAX2 message exchanges, a related issue to CVE-2008-3263.
http://www.securityfocus.com/bid/36275
http://www.securityfocus.com/archive/1/506257/100/0/threaded
http://securitytracker.com/id?1022819
http://secunia.com/advisories/36593
http://downloads.asterisk.org/pub/security/AST-2009-006.html