Security fixes only (since 1.8.4.2):
 * AST-2011-008 (unauthenticated remote crash via SIP/UDP)
 * AST-2011-009 (unauthenticated remote crash via SIP)
 * AST-2011-010 (remote crash via IAX)
 * AST-2011-011 (possible SIP user enumeration)