Layer 3 Adpcm Audio (Reduced Bandwidth Setting); Installing Fax Devices With Atas - 3Com NBX 100 Installation Manual

Layer 3 ADPCM Audio
(Reduced Bandwidth
Setting)
Installing Fax
Devices with ATAs
The overhead for running a device as a Layer 3 device results in a
maximum bandwidth requirement of 54.7 Kbps per party in the
conversation. Thus, a point-to-point call requires this peak bandwidth in
each direction, while a 3-party conference requires a peak of 164 Kbps in
one direction. See Notes A and B.
NOTE A: Silence suppression reduces this requirement on average by
30—40% but can not be assumed when determining the peak
requirements.
NOTE B: The values provided do not include link overhead (e.g., packet
encapsulation, additional bytes for error detection/correction, etc.) which
may be added by the customer's specific interconnection device. This
overhead must be added based upon the device specification and is not
under the control of the NBX 100.
When installing a fax device with a Single-Port Analog Terminal Adapter,
note the following:
A fax device requires twice the bandwidth (150 Kbps) of a voice
I
device.
A fax device must be configured to use Mulaw compression.
I
Problems encountered receiving or sending faxes could indicate
I
network traffic issues.
Some PC fax/modems may not work properly due to the very low
I
latency requirements of such devices.
The most effective way to install a fax device is to install it using a
I
Single-Port ATA connected to a hub card in the NBX 100, or to use a
dedicated switch port for the ATA connected to the fax device.

Installing Fax Devices with ATAs

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