Depending on telephone line conditions and the type of speakerphone the
distant party is using, it may not be possible for the 8412F speakerphone
to operate in full-duplex mode. If the distant party’s speakerphone is a
half-duplex model and both you and the distant party are in
speakerphone mode, the half-duplex speakerphone controls the
communications mode and prevents the 8412F from operating in
full-duplex mode.
To maximize the usefullness of your full-duplex speakerphone, take note
of these following observations about full-duplex speakerphone
operation.
•
The full duplex operating mode requires a small amount of time to
adapt to changes in echo; therefore, you should avoid making any
movements in the vicinity—about a one-foot radius—of the
speakerphone.
•
There are certain echo limits beyond which the speakerphone cannot
effect canceling. These limits are as follows: room echoes beyond 39
milliseconds (standard configuration) and line echoes beyond 24
milliseconds (standard configuration).
•
The speakerphone may automatically reduce the volume in each
direction when both you and the distant party talk at the same time
(double-talk). This volume reduction is necessary to control the
echoes at high volume levels. It is possible for surrounding
conversations and other sounds to trigger double-talk even when you
are not speaking. This condition may lower the loudspeaker volume
at your speakerphone.
•
You must adjust the loudness of your voice to match that of the
distant party’s voice. This action is necessary to cause full-duplex
operation to take place. Sustained doulbe-talk or excessive echo may
cause the speakerphone to drop back into half-duplex operation. This
happens because the speakerphone’s echo cancel circuits cannot
adapt during the double-talk situation.
•
If both you and the distant party are using full-duplex
speakerphones, the sensitivity to both echo path changes and volume
reduction during double-talk is doubled from the sensitivity when
just one full-duplex speakerphone is involved.
1 – 4 Large Screen Speakerphone Manual
Introducing The Large Screen Speakerphone GCA70–349