DEFINITY ECS Release 8.2 Maintenance for R8.2csi
555-233-119 Issue 1
April 2000
Maintenance for csi systems
1-141Troubleshooting Multimedia Call Handling (MMCH)
1
If the input from an endpoint is loc ated too close to the speakers of an endpoint,
then acoustic echo is c reated. The microphone must be moved away from the
speakers.
Normally, if any microphone in the room is moved relative to the speakers, that
site will cause echo until the ech o canceller in the codec retrains itself, some will
require a manual reset. If a PictureTel keypad is configured with external
microphones connec ted to the keypad, then the interna l microphone and
external microphone(s) “s ing” to each other if the “e xt mic” bat switch is s et to
“int mic” on the b ack of the keypad. In this c onfiguration, VAS locked on that site,
and the acoustic “ singing” was inaud ible.
Rate Adaptation
Because of a lack of a cl ear explanation in standards, sometimes end points do
not work well with each other and the DEFINITY MMCH. The MMCH will only
allow a conference to downg rade from 64kbps to 56 kb ps operation on
conferences that have the Rate Adaptation flag s et to y.
When a downgrade does oc cur, information on the Status Conference form
indicates the succ ess or failure of the 64kbps-endp oints that are participants to
properly rate adap t to 56kbps. As a general ind ication that the conference has
rate adapted, the Conference Transfer Rate and Effective Transfer
Rate fields show initial and current transfer rates, respectively. For each 64-kbps
endpoint the column that in dicates Rate Adapt shows an n if the endpoint did
not follow the procedures as spec ified by the H.221. If an endp oint shows y, it did
successfully rate adap t. If an endpoint shows c, it joined the conference at
56kbps.
Once the conference rate ad apts, the endpoints that d o not properly follow suit,
will become audio-only end points. A conference will not rate ad apt from 56 kbps
back to 64 kbp s until all endpoints disc onnect from the conference and it idles.
The PictureTel 1000 Release 1.1C, PictureTel 6.01 software, and the Vistium 2.0
software successfully rate adap t with the MCU. External rate adaptation
techniques used b y VTEL and CLI are known to cause problems with the
endpoint when used with this fe ature.
Endpoint or I-MUX in Loopback Mode
Some endpoints have a loopba ck enable feature. This makes DEFINITY MMCH
data loopback at the MMCH when a connection is in progress. The loopback can
be enabled p rior to or during a connec tion.
The MMCH does not detect the loop and continues to VAS. In most scenarios,
the switch occurs, b ut within a few seconds, the broad caster’s return video
becomes its own image. Onc e the broadcaster stop s speaking, the system
“false” switches to an ap parently random port that was not speaking.