PBX Systems Management and Administration: Performance Management

PBX performance management records and reports are typically available for the following system measurements.

Trunk Usage and Traffic

Trunk traffic records are kept for all inbound and outbound calls and identify the trunk group and trunk channel, time of call, and duration of call. Individual trunk line counters can measure the number of call attempts, blocked trunk lines, and traffic intensity (Erlangs). Outgoing counters can measure the number of outgoing attempts, successful calls overflowing to another route, calls lost due to blocking, blocked trunks in measurement, and traffic intensity (Erlangs). Incoming trunk route counters can measure the number of incoming call attempts, trunks in the measurement, number of blocked trunks in the measurement, and traffic intensity (Erlangs). Similar statistics are measured for two-way trunk routes.

Attendant Consoles

Attendant counters can measure all attendants in the system or individual attendants positions. Record measurements include number of answered calls, number of calls initiated by attendant, accumulated handling time for all calls, accumulated handling time for recalls, accumulated handling time for calls initiated by attendant, accumulated total delay time for recalls, number of answered recalls, number of abandoned attendant recalls, accumulated waiting time for abandoned calls to an attendant, accumulated waiting time for abandoned recalls, and accumulated response time for all types of calls.

Stations

Station counters can measure individual stations or station group traffic statistics such as number of calls, number of stations in the measurement, number of blocked stations in the measurement, and traffic rating (Erlangs).

Traffic Distribution

Traffic distribution across the internal switching network can be measured for each local TDM bus, traffic over each highway bus, and traffic across the center stage switch by each switch network interface link.

Busy Hour Traffic Analysis

Busy hour traffic analysis measurements for trunks, stations, and the internal switch network can be performed. Busy hour traffic intervals can be programmed for any time of day. Erlang ratings are calculated for individual trunk lines, individual trunk groups, and all trunk groups. CCS ratings are calculated for individual stations or groups of stations.

Processor Occupancy

System call processing performance is measured in terms of BHCs (attempts and completions). The percentage of maximum call processing capacity is reported for programmed intervals. Threshold reports can be generated to monitor system load factors.

Threshold Alarms

For a variety of system hardware devices, it is possible to define a congestion threshold value and measure generated alarms. Alarms are recorded in an alarm record log. The types of devices that can be tracked are tone receivers, DTMF senders and receivers, conference bridges, trunk routes, and modem groups.

Feature Usage

Feature usage counters for selected station features (e.g., call forward, call transfer, add-on conference) and attendant system features (e.g., recall, break-in) can be measured and reported for programmed intervals.

VoIP Gateways

IP-PBX systems collect and store data to track the usage and performance of IP gateway devices, IP phones, and VoIP trunk calls. VoIP information reports include tracking of IP gateway devices and calls that pass through each gateway, gateway congestion, assignment of services or routes to gateways, tracking of phone numbers dialed or originating off-site numbers, and IP gateway addresses.

CDR

CDR data is compiled for all successful incoming and outgoing trunk calls. Call records can be stored in multiple formats (fixed and programmed) per output device. Fixed formats typically conform to standards published by leading call accounting software suppliers, or are proprietary to the PBX system. Programmable formats provide a flexible means to incorporate new data elements in the call record. A variable format allows a record to be defined in terms of its content (from a set of available data elements) and the position of the data elements in the record. This method can be used to construct custom formats.

A system administrator may define programmable CDR formats based on available CRD field data records. Call record fields typically include:

• Date

• Time

• Call duration

• Condition code (categorizes information represented in the call record)

• Trunk access codes

• Dialed number

• Calling number

• Account code

• Authorization code

• FRL for private network calls

• Transit network selection code (ISDN access code to route calls to a specific interexchange carrier)

• ISDN bearer capability class

• Call bandwidth

• Operator system access (ISDN access code to route calls to a specific network operator)

• Time in queue

• Incoming trunk ID

• Incoming ring interval duration

• Outgoing trunk ID

Reports can be generated for any or all of the call record field data.

CDR data is not usually compiled for intraswitch calls (station to station, station to attendant), calls terminated by busy signals, and calls with no answer. When CDR was introduced as a system option in the early 1980s, memory storage was expensive. Any call that did not incur a direct expense was not recorded and stored. Today, PBX systems based on nontraditional designs, such as CTI-based server systems, can collect, store, and process these data records for reporting purposes. Traditional circuit switched PBXs may optionally record a limited number of intraswitch calls for select calling stations or capture data for all calls using optional CTI solutions.

CDR records and call accounting reports are vital to the monitoring and management of the PBX system. It is important to monitor call costs and usage to:

• Bill system subscribers for their communications network use

• Budget and allocate usage charges by department

• Resell telephone services to outside clients

• Monitor PBX effectiveness

• Gather statistical data for performance benchmarking

• Prevent or minimize telephone system abuse and unauthorized access

• Verify monthly service provider bills

There are several optional PBX reports that are useful to system administrators.

Directory

Directory records can include each subscriber’s name, with a variety of phone numbers such as primary, published, listed, emergency, and alternate, and authorization code information, job title, employee number, current employment status, and social security number.

Inventory

Inventory records and management is used to administer any kind of inventory product part: PBX common equipment (cabinets, carriers, circuit cards), voice terminals and module options, jacks, and button maps. The reports allow administrators to accurately re-charge items. Inventory can be tracked by data such as user, system (PBX or other networks), jack, serial number, asset tags, trouble calls, recurring and nonrecurring costs, and general ledger codes. The inventory management system also includes records containing the following data: purchase date, purchase order number, depreciation, lease dates, and manufacturer and warranty information.

Cabling

Cabling records keep track of all cable, wire pairs, distribution frames, wiring closets, and all connections (including circuits) down to the position and the pair level. Records include starting and ending locations, description, type, and function. Individual cable lengths are maintained and automatically added, as is the decibel loss for the entire path. Information can be provided on the status of all cable runs and the number of pairs they contain, the status of the pairs, and the type of service they provide.