Polycom ViewStation FX4000 User Manual page 137

© Polycom, Inc. 2002
Chapter 4 - Advanced Configuration for your Network Environment
2. Press the SELECT button on the remote control to change the
status of the channel.
PRI Channel Selection Information
Outgoing Call. For an outgoing call, the ViewStation FX or VS4000
uses the first active and available channel starting with the lowest
number from the channel range (1-23 for a PRI T1 and 1-30 for a PRI
E1). If an additional channel is needed, the system chooses the next
incremental number. For example, if channels 1 through 7 are
inactive, but 8 is active and available, then 8 is the first channel that
can be used by the ViewStation FX or VS4000 to place an outgoing
call. If an additional channel is needed, the system will use the next
available active channel in the range (which could be 9, and so on).
Incoming Calls. For incoming calls, the ViewStation FX or VS4000
may use the highest numbered channel in the range and, if needed,
proceed to the next channel number in a descending order,
depending on the type of third-party equipment attached to the
system. For example, an incoming call arrives on channel 23, then
22, 21, and so on.
Dedicated full PRI T1 or E1 Line. All channels should be active for
a full T1 or E1 line dedicated to your FX or VS4000.
Fractional PRI T1 or E1. Channel selection should be handled by
your PRI network administrator.
PRI E1 Channel Information
The PRI Status screen (for E1) shows 30 channels. However, E1
trunk lines have 32 time slots, numbered 0 - 31. Time slot 0 is used
for framing, and time slot 16 is used for call signaling (the D
channel). The remaining 30 time slots are used as bearer (data)
channels.
In call signaling between Polycom equipment and the switch, these
channels are numbered 1-15, 17-31. But the PRI Status screen
numbers these channels contiguously in the range 1-30. Therefore,
on the PRI Status screen, channels 1-15 control the status of time
slots 1-15, and channels 16-30 control the status of time slots 17-31.
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