Polycom 1500/1800/2000/4000 Monitoring ISDN/PSTN Participants, Endpoint Disconnection Detection

Conference and Participant Monitoring

H.323 Endpoint Disconnection Detection

In versions previous to version 8.4, when an H.323 endpoint disconnected, round trip messages were still received, even when a gatekeeper was deployed. Because of this, the MCU failed to detect the endpoint disconnection.

From version 8.4 onward, the MCU detects H.323 endpoint connection or disconnection by monitoring RTCP/RTP messages reception using either the audio or video channels. When these messages are not received within a predefined timeout interval, the endpoint is considered disconnected. Therefore as long as either RTCP or RTP messages (interchangeably) are received on either of the video or audio channels, the endpoint is considered connected.

If no messages are received through either channel within the predefined time out interval, the endpoint is disconnected, and a disconnection message, H.323 remote stopped responding, is sent to the endpoint.

No channel disconnection detection occurs while an endpoint’s video or audio are muted, or while the endpoint is put on hold.

In audio calls, only the audio channel is polled for RTCP/RTP messages.

System Configuration Flag

The time out used for H.323 endpoint disconnection detection is controlled by the

DETECT_H323_EP_DISCONNECT_TIMER System Flag which must be added to the System Configuration to view or modify its value.

Range: 16 - 300 (4-second units). Values indivisible by 4 will be rounded upward. Flag values between 0 and 15 disable the flag functionality.

Default: 20

For more information see , and Modifying System Flags.

Monitoring ISDN/PSTN Participants

Using the Participant Properties dialog box, you can monitor and verify the properties of an ISDN/PSTN participant. The dialog box’s tabs contain information that is relevant to the participant’s status only while the conference is running and is used to monitor the participant’s status when connection problems occur.

Maximum line rate at which ISDN endpoints can connect to a conference is 768 kbps.

The table below lists the audio algorithms that are supported for ISDN participants according to their connection bit rate

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