Polycom ViewStation EX4000 - Manual (Page 40)

Integrators’ Reference Manual for ViewStation EX, ViewStation FX, and VS4000
30 www.polycom.com
Channel Selection
For outgoing calls, the system uses the lowest-numbered available
channel (1-23 for a PRI T1 and 1-30 for a PRI E1). If an additional
channel is needed, the system chooses the next higher-numbered
channel. For example, if channels 1 through 7 are unavailable, but 8
is available, the system uses channel 8 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).
For incoming calls, the system uses the highest numbered channel
that is available. If another channel is needed, the next lower
channel number is used.
PRI E1 Channel Information
The PRI Status screen for E1 shows 30 channels. However, E1 trunk
lines have 32 timeslots, numbered 0 - 31. Timeslot 0 is used for
framing, and timeslot 16 is used for call signaling (the D channel).
The remaining 30 timeslots 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 in the range 1-30. On the PRI Status screen,
channels 1-15 control the status of timeslots 1-15, and channels 16-30
control the status of timeslots 17-31
.
Dedicated Full PRI T1 or E1 Line
All channels should be active for a full T1 or E1 line dedicated to
your ViewStation FX or VS4000.