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Introduction to Westbay Traffic Calculators
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The programme consists of a single window, with tabs to select between
the Erlang B Calculator, the Extended Erlang B Calculator, the Erlang C Calculator and the
Call Minutes Calculator The package also has the ability to display and print the
results of any calculations you have made during the previous week.
| This product does not
support Voice over IP bandwidth calculations. For VoIP calculations, please see our VoIP Select Windows product. |
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Westbay Traffic Calculators now includes Erlang for Excel free of charge. This is a
Add-In for Microsoft Excel higher that allows Erlang B functions to be included in your
own spreadsheets.
The calculators, which require Microsoft Windows 95 or higher (including
Windows Vista), are available for 139 US Dollars. Click here to find out how to purchase. |
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| The Erlang B Calculator is based on the Erlang B traffic model and is
used to work out how many lines are required on a trunk group if the traffic and the
required grade of service are known. Traffic values can be entered in either Erlangs or
C.C.S. (Centi-call seconds). The calculator works up to 90,000 Erlangs / Lines! 
"How many lines do I need in a trunk group if that
trunk group is offered 200 Erlangs of traffic during its busy hour and I accept that 1.2%
of calls will fail due to blocking?" Answer - 220
Unlike similar products, you can also carry out these calculations in reverse. For
example, you can find out what the probability of blocking would be for a given busy hour
traffic figure and trunk group size. If you know two of the variables, you can work out
the third. You can view the fully illustrated
User Guide now to find out more about how the calculator works and study example
calculations.
Technical specification available.
Why not try an online version of this calculator
to see how it works. |
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| The Call Minutes Calculator is used to work out how many lines a trunk
group requires if the number of minutes of traffic offered to that trunk group in one day
are known. Reverse calculations are also supported which allow you to estimate how many
minutes of traffic a trunk group can be offered per day. The calculator works up
to 30,000,000 call minutes per day! 
"How many lines does a trunk group need? It is offered
50000 minutes of traffic per day and I accept that 3% of calls will be blocked. I estimate
that 19% of daily calls are made during the busiest hour?" Answer - 168
Reverse calculations are also possible to help you work out how many minutes of calls a
trunk group can be offered. More information is available in the fully illustrated User Guide.
Technical specification available. |
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Extended Erlang B Calculator
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| The Extended Erlang B Calculator is very similar to the Erlang B
calculator but also takes into account the additional traffic created by callers
immediately trying to redial a number if their call is blocked. This calculator produces
slightly more accurate results if no overflow facilities are available on a trunk group.
As with the Erlang B calculator, reverse calculations may be carried out and the
calculator works up to 90,000 Erlangs / Lines! 
"How many lines does a trunk group require if it is
offered 200 Erlangs of traffic during its busy hour and I accept that 5% of calls will
fail due to blocking, half of which are immediately retried?" Answer - 207
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| The Erlang C Calculator can be used for calculations involving the
queuing of telephone calls. This means that it offers a way of calculating the number of
call centre agents or switchboard operators required if the call volumes are known. The
calculator works up to one million calls per hour and 10,000 agents! 
"What percentage of calls will be answered within 20
seconds if my call centre receives 650 calls in an hour of average duration 150 seconds
and my call centre is manned with 34 available agents?" Answer - 94%
The Erlang C Calculator simplifies the complicated calculations required to predict and
analyse call centre performance. There are a number of variables involved in such
calculations including the number of calls received per hour, the average duration of the
calls and the required answering performance.
The calculator can be used to answer such questions as:
- How many agents does a call centre need?
- How many calls can the operators handle?
- What duration of calls can be handled?
- What will the average delay to incoming calls be?
- How many calls will be answered within target?
You can view the fully illustrated User
Guide now to find out more about how the calculator works and see how these questions
are answered.
Technical specification available.
Why not try an online version of this calculator
to see how it works (requires JavaScript). |
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| Westbay Traffic Calculators is provided with a fully formatted and illustrated User
Guide which is distributed electronically in the form of Web pages. This User Guide
explains how to use the calculators and offers many examples of their use. There is also a
Windows help system installed with the software. You can view the fully illustrated User Guide now to find out
more about how the calculator works and study example calculations.
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Purchasing
Westbay Traffic Calculators
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Westbay Traffic Calculators, which comprises the four calculators described above,
costs 139 US Dollars for a single user licence. You can pay
using any major credit card. You will also receive a free copy of Erlang for Excel. This is a Add-In for
Microsoft Excel that allows Erlang functions to be included in your own spreadsheets.
| This product does not
support Voice over IP bandwidth calculations. For VoIP calculations, please see our VoIP Select Windows product. |
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Transactions are with Westbay Engineers Ltd. (our parent company) and
are handled on the secure server of WorldPay, our e-commerce
supplier. You can have the software running on your PC five minutes from now!
(In exceptional circumstances, online payments can take up to one working day to complete)
Our price list is fixed in US Dollars. During the ordering process, you
will be able to change this to the equivalent amount in Euros or Pounds Sterling.
American Express and Diners Club transactions are only available in Pounds Sterling - the
equivalent rate will automatically be presented to you before you purchase. |
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Please choose a licence type
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| Please take a moment to consider the type of licence you require. Your honesty
in this matter helps us to continue developing our products. Software piracy is
illegal. |
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| Alternatively, if you would prefer to pay by cheque or
money wire, please contact us. |
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| Try looking in the FAQ
(Frequently Asked Questions). Someone else may already have asked the same question.
Failing that, please send us an email. |
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Erlang B / Ext. Erlang B |
Erlang C |
Call Minutes |
| Operating system |
Windows 95, 98, ME, NT4, 2000, XP or Vista. |
| Traffic model used |
Erlang B / Ext. Erlang B |
Erlang C |
Erlang B |
| Operational limits |
BHT 90,000 (max) Erlangs
Blocking 0.001 - 0.500
Lines 90,000 (max)
Retries 95% (max) |
ACD Agents 1 - 10000
Calls per hour 1000000 (max)
Duration 10000 (max) seconds |
1 - 30000000 mins. per day
Blocking 0.001 - 0.500
Lines 90,000 (max) |
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