ISDN
Call-By-Call Overview
7-12 Strata DK Programming 5/00
Call-by-Call Min/Max Control
There are two variables that can be programmed for each trunk group to ensure optimum call
utilization. These are the minimum and maximum values.
♦ The minimum (min.) value is defined as the minimum number of B-channels in reserve that
are necessary to ensure that a given trunk group can adequately service calls. The default value
is zero.
♦ The maximum (max.) value is the maximum number of B-channels that are necessary to
ensure that a given trunk group can adequately service calls during a peak period. The default
value is 23.
The min and max values must be determined by you based on the traffic volume and environment.
Here are some guidelines:
♦ The total number of lines assigned to all trunk groups as minimums should not exceed the
number of B-channels in the channel group. For example, if there are 23 B-channels in the
channel group, the total sum value programmed as minimum in all trunk groups should not
exceed 23.
♦ The maximum value typically never exceeds the total of the subscribed B-channels for the
channel group. The programmed maximum value is typically used to limit the total number of
shared lines available to a given trunk group.
Example 2
This example shows how to determine the maximum number available to a trunk group.
Refer to Figure 7-3. Add the min. values from the other trunk groups, then subtract that sum from
the number of B channels in the channel group. The remainder is the total number of lines
available for that trunk group. This is outlined in steps 1 and 2 below.
Maximum trunk group values are set in Program
*
67-4. Minimum trunk group values (reserved)
are set in Program
*
67-3.
Channel Group 1
Max. = 23
Min. = 8
Trunk Group 1
Max. = 12
Min. = 5
Trunk Group 3
Max. = 7
Min. = 3
Trunk Group 2
4917
1. Determine the total number of lines
available to Trunk Group 1.
2. Subtract from other Trunk Groups’
min. values from the number of
B-channels in that Channel Group.
3
Trunk Group 2 Min.
+ 5
Trunk Group 3 Min.
8
Min. Value for Trunk Groups 2 & 3
23
B-channels in Channel Group 1
- 8
Min. Value for Trunk Groups 2 & 3
15
Lines available to Trunk Group 1
(8 reserved + 7 shared)
Note Even through the max. value is
set for 23 channels, only 15
channels are available for
Trunk Group 1.
Figure 7-3 Example 2 – Shared Trunk Lines
