"This Recommendation defines a mechanism for media communication between two ITU-T H.323 entities@ separated by one or more NAT/FW devices. This Recommendation addresses NAT/FW traversal for RTP@ for RTP encrypted using ITU-T H.235 and for SRTP media streams. NAT/FW traversal for media transported by other protocols is for further study. It also defines a mechanism to use the same transport address for several media channels@ which permits reduction of the number of ""pinholes"" opened in the NAT/FW device and reduces the number of Media Channel and Media Control Channel transport addresses used by ITU-T H.323 entities."