PhoneCalc description

T-Calc is an advanced call-centre calculator, with all the standard call-centre calculations such as Erlang-C, plus Mitan-C for abandoned calls, agent shrinkage calculations, several other queueing models. T-Calc is designed to be particularly useful for educational and training purposes.

 Contents

  Summary display

  The queueing triangle

  Queueing models

  Input panels

  Agent shrinkage calculator

  Call answering

  Agent occupancy

  Agent attendance

  What-If charts



Click on the image for a larger picture.

Summary display

The summary display shows all the important statistics displayed within an easy-to-understand diagram of a simple call-centre. The average number of calls waiting is shown by a telephone symbol for each call or fraction of a call.

Back to top


The queueing triangle

The queueing triangle refers to the three aspects of a queueing situation which are related by a formula such as Erlang-C or Mitan-C. In general you specify any two of the corners, and the queueing formula determines the remaining corner.

It is certainly possible to specify service-level targets and number of agents, then use the queueing triangle to calculate the workload which can be handled by that number of agents while achieving the service-level target. However, the typical approach is to forecast thge workload, specify the traget service-level, then calculate how many agents are needed.

Back to top


Queueing models

T-Calc provides the following queueing models.

Basic Queued Calls (Erlang-C)

Basic Lost Calls (Erlang-B)

Basic Call Retry (Erlang-B Extended)

Abandoned Calls (Mitan-C)

Limited Queue Size

Overflow on Timeout

Advanced Call Retry.

back to top..


Input panels

There are three input panels, each corresponding to one of the corners of the queueing triangle. Whenever an input value is changed, recalculation is done and diagrams, charts, and other displayed values are updated.

"Workload" includes call rate and duration, plus other caller characteristics such as waiting tolerance and retry behaviour.

"Targets and limits" is where service-level and loss-rate targets are specified, together with queue-size or waiting-time limits.

"Agents" selects the criteria to be used for calculating the number of agents needed, and whether shrinkage factors are to be included.

Back to top



Click on the image for a larger picture.

Agent shrinkage calculator

The shrinkage calculator shows how much agent time is taken up with non-call-handling work such as meetings and coaching, time for breaks and meals, and other factors such as absenteeism. The calculator shoes how much of an agents time is a

Back to top


Call answering

There are three detailed charts about call answering.

"Answering statistics" shows the proportion of calls answered immediately, within target, late, or not answered.

"Waiting-time distribution" shows the complete distribution of waiting-time, and the actual target in use. This shows whether, for example, "80% in 15 seconds" is equivalent to "90% in 10 seconds".

"Abandon-time and tolerance" applies to Mitan-C, and shows the relationship between "tolerance" and time-to-abandon ans abandon rate.

Back to top


Click on the image for a larger picture.

Agent occupancy

This chart and associated table shows the proportion of agent time spent on talk, wrap, and so on, and any shortfall or excess of agents compared to the number of agents needed for the current performance targets. Occupancy can be displayed

Back to top



Click on the image for a larger picture.

Agent attendance

The agent attendance chart shows, for the current absenteeism rate, how likely it is that a particular number of agents will actually attend.

Back to top



Click on the image for a larger picture.

What-If charts

The chart shows shows the effect of varying one of the parameters of the scenario. One of several parameters may be chosen to be the variable parameter. The current value of the variable parameter corresponds to the middle of the horizontal

Back to top