Print This Page

H.323 ports

IP Ports and Protocols used by H.323 Devices

This Port
389 statique - TCP ILS Registration  (LDAP)
1503 statique - TCP T120
1718 statique - TCP Gatekeeper Discovery
1719 statique - UDP Gatekeeper RAS
1720 statique - TCP H323 Call Setup
1731 statique - TCP Audio Call Control
1024-65535 Dynamique - TCP H245 Call parameters
1024-65535 Dynamique - UDP RTP (Video Data Streams)
1024-65535 Dynamique - UDP RTP (Audio Data Streams)
1024-65535 Dynamique - UDP RTCP (Control Information)

H.323 and Firewalls

Microsoft NetMeeting and Firewalls

When you use NetMeeting to call other users over the Internet, several IP ports are required to establish the outbound connection. If you use a firewall to connect to the Internet, it must be configured so that the following IP ports are not blocked.

This Port   
Is Used For
389 Internet Locator Server (TCP)
522 User Location Service (TCP)
1503 T.120 (TCP)
1720 H.323 call setup (TCP)
1731 Audio call control (TCP)
Dynamic H.323 call control (TCP)
Dynamic H.323 streaming (RTP over UDP)

To establish outbound NetMeeting connections through a firewall, the firewall must be configured to do the following:

  • Pass through primary TCP connections on ports 389, 522, 1503, 1720 and 1731.
  • Pass through secondary TCP and UDP connections on dynamically assigned ports (1024-65535).

The H.323 call setup protocol (over port 1720) dynamically negotiates a TCP port for use by the H.323 call control protocol. Also, both the audio call control protocol (over port 1731) and the H.323 call setup protocol (over port 1720) dynamically negotiate UDP ports for use the by H.323 streaming protocol, which is the RTP. In NetMeeting, two UDP ports are determined on each side of the firewall for audio and video streaming, for a total of four ports for inbound and outbound audio and video. These dynamically negotiated ports are selected arbitrarily from all ports that can be assigned dynamically.

NetMeeting directory services require either port 389 or port 522, depending on the type of server you are using. ILSs, which support LDAP for NetMeeting, require port 389. ULS, developed for NetMeeting 1.0 requires port 522.

Previous page: Phone Conference Rooms
Next page: SIP - IAX ports