The H323 Settings provide information on the H.225 RAS receive UDP port and H.323 TCP port range, enable H323 specific options as well as allows to enable the NAT traversal for the H.323 traffic.
The text field UDP Port indicates the H.225 RAS UDP (User Datagram Protocol) receive port number. UDP port cannot be in the selected RTP/RTCP port range for FXS and IP lines (see RTP Settings) otherwise error appears.
The text fields TCP Min Port and TCP Max Port text fields are used to indicate the TCP (Transmission Control Protocol) receive port range for H.225 call signaling and H.245 media negotiation. The port defined in the TCP Min Port text field will be used for accepting the incoming direct H.323 calls.
There are three ways to set up a H.323 call: a separate H.245 channel, fast connect and tunneling. However, it is not always possible to use fast connect or tunneling and a terminal can at any time switch back to a separate H.245 channel.
Fast Connect checkbox enables media negotiation handled by the H.225 call signaling messaging without opening H.245 channel. Fast Connect reduces the number of transmitted H.323 messages and allows the media channels to be operational before the connect request is sent and the telephone rings.
Tunneling checkbox enables H.245 channel to be sent within the H.225 call signaling channel.
H323 timers parameters group allows to specify TCP and Setup timeouts and provides following components: