Multimedia Call Handling (MMCH)
Issue 4 May 2002
5-55555-233-123
PRI D-Channel Backup
A somewhat unlikely source of call stability problems occur where the translations
for PRI D-channel Backup between two non-MCU switches were incorrect. As an
example, on switch A, DS1 1A10 was designated as the primary source, and on
switch B, the corresponding DS1 was designated as the secondary source. When
scheduled maintenance was run on the switch that had an active standby
D-channel, an audit disconnected some calls using the link. The problem was
corrected when the D-channel primary/secondary assignments matched.
Processor Duplication on the PBX
Do not enable the PI link switch on scheduled maintenance. This can cause link
stability problems on the Accunet Bandwidth Controller (ABC).
Voice-Activated Switching Problems
Voice-activated switching on the DEFINITY MMCH does not follow the loudest
talker. The MMCH queues all speaking parties and selects a new video
broadcaster (the second-oldest speaking party) when the oldest speaking party
has stopped talking. The new broadcaster will see the last speaker as its video.
The system can also “learn” about the noise coming from an endpoint to help
prevent false switches, adapting both to noise level and repetitive sounds such as
a fan. This adaptation occurs over approximately 10 seconds.
No Switching, Full Motion Video
If a room is excessively noisy, the DEFINITY MMCH may receive sufficient audio
signal to conclude that there is a speaker present. Use the Status Conference x
form to determine if the MMCH thinks an endpoint is talking. The MMCH sets the
Ts field to t for each endpoint if there is voice energy detected. This endpoint
may have to mute when nobody at the site is speaking to allow the conference to
proceed normally. Remind the customer that it may be necessary to mute if a side
conversation is going on in the background, just as one would do in an audio
conference. If the system does not switch broadcasters even after the current
broadcaster has muted, check the conference administration using the display
conference X command to ensure that the conference is in voice-activated mode.
Also verify that parties who were speaking are valid video sources as described in
the “Calls Terminate with No Video” section above.
The See-Me feature (MCV) can also cause VAS to “lock-up.” An endpoint can
activate MCV to force their site to become the broadcaster. If they do not disable
the feature when finished, the system remains in this mode indefinitely. The
status conference X command shows that MCV is in effect by displaying
av in
the Video Status (Vs) column. Page 3 of the Status Conference X Endpoint Y form
also has a
Broadcaster field that indicates MCV is in effect with (SEE-ME) as
the broadcaster. The same scenario can occur in a CHAIR or UCC-controlled
conference with a designated broadcaster. In this situation the CHAIR/UCC has
not released the designated broadcaster and returned to VAS mode. If there is a
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