Size of the queue for the ISDN-PRI CBC trunk group. If zero is displayed, then no queue is administered. Hence, the other queue measurements is also zero. If the queue is administered, then it serves all of the network services/features administered for the trunk group. However, its functional operation is somewhat different than the queue used with conventional trunk groups. When a particular service/feature uses its allotted maximum number of channels, then any additional call attempts are queued, even though not all of the trunks are currently in use. If the queue is already full, any additional call attempts simply overflow with the caller receiving reorder tone.

Recommendations: Since one service/feature generally does not experience peak traffic the same time as another service/feature, there is an averaging effect. Furthermore, the queue size for a CBC trunk group need not be much larger than for a non-CBC trunk group. The Queue Size should be larger than the trunk group size; but, typically, not more than three times as large as the trunk group size.

The total number of calls entered the CBC trunk group queue during the hour.

The total number of calls denied access to a trunk, found the queue full, and the caller received reorder tone.

Suggested actions: Generally, this field displays the number 0. If this field indicates a high number, then the queue size may be too small, more trunks may be needed so fewer calls will queue, or the UAP may be too restrictive (for example, some of the Min Chn values may be too high, or some of the Max Chn values may be too low). Also, see Suggested actions in the % TBM description.

The number of calls removed from the queue by either the system or the user. The system automatically removes calls from the queue after 30 minutes. A user may abandon that call by canceling the Automatic Callback feature (set earlier to place their call in the queue).

Suggested action: Recall that a trunk group and its associated queues are sized to accommodate peak-hour traffic loads. Typically, this field indicates a small number. However, a large number generally indicates the queue size is too large and people are abandoning because they remained in queue for a long time. Consider adding more trunks so fewer calls queue.

The number of trunks in the trunk group out of service at the time the measurements are collected. An individual trunk may be taken out of service either automatically by the switch whenever an excessive number of errors occur, or by maintenance personnel to run diagnostic tests.

Suggested action:If the trunks were removed from service by the switch, then the appropriate maintenance personnel should be notified. The objective is to keep all members of a trunk group in service. Generally, you should not make adjustments to the CBC trunk group because of Out of Service trunks, but should get those trunks returned to service.

A list of the Usage Allocation Plan numbers followed by a list of the durations (in minutes) each plan was in effect during the measurement interval. The Number field can display up to a maximum of six plan numbers. A maximum of three different UAPs (identified by the numbers 1, 2, and 3) may be defined for each trunk group. All three plans are defined on Page 3 of the trunk group screen. Page 4 of the corresponding trunk group screen is where you administer plan assignments.

Each CBC trunk group is administered with either fixed allocation or scheduled allocation. If fixed, it remains in effect continuously. If scheduled, the designated plans are activated on a per-day and time-of-day basis determined by the schedule.

The names of up to 10 services/features and the special identifier other for which the associated measurements are reported.

Minimum Number of Channels. The minimum number of channels in the ISDN-PRI CBC trunk group allocated to the specified service/feature at the time the measurements are collected.

Maximum Number of Channels. The maximum number of channels in the ISDN-PRI CBC trunk group allocated to the specified service or feature at the time the measurements are collected.

The sum of time, in hundred-call-seconds (CCS), for all channels used by the specified service/feature during the measurement interval.

Total Seizures. The total number of incoming and outgoing calls that requested the specified service/feature through the ISDN-PRI CBC trunk group.

Incoming Seizures. The total number of incoming calls that requested the specified service/feature through the ISDN-PRI CBC trunk group. For two-way and outgoing trunks, the number of Outgoing Seizures can be calculated as follows:

Tandem Seizures. The total number of trunk-to-trunk call seizures using this Service/Feature.

Overflow Services/Features. The number of calls that requested the specified service/feature but denied because the calls arrived under the following conditions:

• The specified service/feature is at or above its minimum channel allocation and below its maximum allocation.

• There are idle channels available in the trunk group, but they are reserved to meet the minimum channel allocation for other services/features.

Suggested actions:

• Investigate the possibility of raising the Min Chn requirements for this service/feature.

• Investigate the possibility of increasing the number of members for the trunk group.

• Determine whether or not the Min Chn assignments for the other services/features are appropriate. For example, if the column % TBM displays a high number for one or more of the other service/features, then you can lower the minimums (for one or more of the other services/features). This makes more trunks available for this service/feature.

Overflow maximum. The number of calls not carried because the calls originated at a time when the service/feature already used-up its allotted maximum number of channels. In this case, the trunk group may still have trunk members available for the other services/features.

Suggested actions:

• Investigate the possibility of raising the number administered in the Max Chn field. This is only possible provided the free pool is not exceeded. To determine whether or not you have more trunks available for a S/F calculate the following:

  

  For example, use the above equations with the data in the formula as follows:

  

• Consider adding more trunks to the trunk group and increase the maximum for the identified service/feature.

Percentage of Trunks Below Minimum. The percentage of time during the polling interval that the number of channels in use by the specified service/feature is below the specified minimum.

Percentage All Trunks Busy. The percentage of time (0 to 100%) during the measurement interval that the specified service/feature could not get a channel because of at least one of the following reasons:

• All trunks in the ISDN-PRI CBC trunk group are busy on a call or busied-out by maintenance.

• This service/feature is above its minimum; and all available trunks are reserved for other features/services below their minimums.

• The specified feature or service is at its maximum number of channels.

Suggested actions:

• A number in the Ovf TG field indicates the physical maximum number of trunks is exhausted. Unless the trunk group is the last preference in the routing pattern, overflow is to the next trunk group. Otherwise, the obvious choice is to add more trunks to the trunk group.

• If the Ovf S/F field indicates a problem (for example, a significant number), refer to Suggested actions in the Ovf S/F description.

• If the Ovf Max field indicates a problem (for example, a significant number), refer to Suggested actions in the Ovf Max description.

Percentage Outgoing Blocking. The ratio of outgoing calls not carried for a specified service/feature to the outgoing calls offered by the service/feature. For an ISDN-PRI CBC trunk group without a queue, the calls not carried are those calls that find all facilities busy for the specified service/feature. For an ISDN-PRI CBC trunk group with a queue, the calls not carried are queue abandons plus those calls that find all facilities for the specified service/feature busy and cannot be queued because the queue is full.

Suggested actions:

• Look at the % ATB column and identify any service/feature with a high value. Follow the Suggested actions in the % ATB description.

• You can increase the length of the queue rather than adding more trunks. Subsequently, you should monitor the Queue Abandonments field to insure it stays within reasonable limits.

• If conditions are such that Item 1 above is not appropriate, you may find it necessary to add more trunks.