"This week, Morganville, N.J.-based Ranch Networks announced the
development of security code for Asterisk, the open source VoIP
project, that allows enterprises to combine Asterisk with Ranch
appliances. The code is certified by Huntsville, Ala.-based Digium
and is available in the latest Asterisk version, number 1.2.3.
"The code uses a standard developed by the IETF called Middlebox
Communications to open firewall ports only when a call is actually
in progress. This should make enterprise firewalls far more
secure..."