Inbound H.323 Calling Port Ranges for devices not registered to the service network

The service network supports calling to rooms and subscribers from H.323 devices that are not registered to the service network.

The service supports inbound URI (Annex O) and IP address dialing.
Some dialing examples include:

  • Direct IP dialing to the IVR at or and then entering the conference ID via DTMF to join a Virtual Meeting Room (VMR)
  •<conferenceID> example:
  • <conferenceID>@ example: 87654321@
  • <conferenceID> example:
  • Video URI addresses for Users or VMRs example: or

The service network uses multiple gatekeepers within our PoPs for H.323 call processing.  These gatekeepers use different port ranges than the endpoints and soft clients registered directly to the service.

To properly route calls geographically to the closest PoP we use some gatekeepers solely for signaling purposes (H.225/Q.931) and other gatekeepers for both signaling and media (H.245, RTP).

H.323 Application Layer Gateways (ALG) should also be disabled on edge firewalls, routing and switching as they can negatively interfere with the processing of calls in and out of the network.

For H.323 devices that do not have static firewall rules configured on inbound ports, we cannot guarantee signalling and media during calls will perform as expected.

These ports are used by the service network’s H.323 gatekeepers:

  • H.323 Call Signaling Port: 1720 TCP
  • H.245 Signaling: 33000 to 39999 TCP
  • Media port range: 11050 to 39999 UDP

For security policies limiting the IP addresses, please refer to the "Calling network" section of the firewall rules (located here) for the latest list of IP ranges used by the service network.

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