AT&T MERLIN LEGEND Communications System PBX System Planning Manual page 84

Trunks
B-Channel Groups
Planning Form Instructions
Under the "Timers and Counters" heading on Form 3c.
1.
To change the factory setting for any timer or counter, write the new
threshold in the "Change To" column.
2.
To keep the factory setting, leave the "Change To" column blank.
To make the most effective use of ISDN-PRI service, assign B channels
(channels 1 through 23) to groups. Once you establish B-channel groups, you
can associate the channels used for ISDN service so that calls can be placed
and received on the associated B channels.
Up to 69 B-channel groups can be established. Each B channel, and channels
used for ISDN service, can be assigned to only one group. Each group can
contain up to 23 channels, and all channels within each group must signal
through the same D channel (connected to the same 100D module).
Assign B channels in the order that the system should search for an available
channel. To minimize call attempts on the same channel, the best arrangement
is the opposite order of the hunting arrangement furnished by the ISDN-PRI
service provider.
Since B channels are not associated with any trunk number or logical ID, they
can by identified only by use of the control unit slot and port number.
Planning Form Instructions
Determine which channels to group and record each group on Form 3c,
page 4, "B-Channel Groups."
Note: Page 4 holds the programming information for two B-channel groups.
Duplicate the form if more groups are planned.
In each column:
1.
Write the group number (1-69) next to the "Group No." heading. Start with
1 and number sequentially.
2 .
Write the slot and port number of each B channel assigned to the group.
(Refer to the "Control Unit Diagram," on Form 1.)
When programmed for ISDN-PRI, the single DS1 jack on the 100D module
supports 23 channels, or ports. (The 24th channel transmits signaling
mode information.) To determine the port number, assume that port 1 is at
the bottom of the module to which you are assigning B channels.
Note: If you have completed the "Non-Complex Configuration" pages of
Form 3c, transfer the slot and channel (port) information from that form.
For all channels you plan to associate with the group:
3 .
Transfer the information from PBX System Form 2c, System Numbering-
Trunks Jacks to Form 3c. Write the logical ID and trunk number in the
applicable column.
Trunk Options 3-29