Free Erlang traffic calculators

The world's first online Erlang traffic calculators

Telecom Traffic Online
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Erlang traffic calculators to assist in voice over IP calculations

Westbay Traffic Calculators costs just 98 US Dollars and includes four traffic engineering calculators in one package. They assist in trunk group dimensioning and call centre staffing analysis. Historical reporting and printing is also included.

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Introduction to Westbay Traffic Calculators

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 product includes support for C.C.S. (centi call seconds) and has the ability to display and print the results of any calculations you have made during the previous week.

Westbay Traffic Calculators includes Erlang for Excel free of charge.   This is a Add-In for Microsoft Excel that allows Erlang B functions to be included in your own spreadsheets.

"I recommend this product highly"
Computer Telephony Magazine

"[This product] is useful, functional and accurate."
Robert Scott Read, Consultant, Traffic Engineering.

The calculators are available for 98 US Dollars.  Click here to find out how to purchase.

Erlang B Calculator

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!

Erlang B on Windows
"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.

Extended Erlang B Calculator

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.

Extended Erlang B on Windows
"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

Erlang C Calculator

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 required if the call volumes are known. The calculator works up to one million calls per hour and 10,000 agents!

Erlang C on Windows
"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.

A free online version of this calculator is available for you to try.

Call Minutes Calculator

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!

Erlang B on Windows
"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.

Documentation

Westbay Traffic Calculators is provided with a fully formatted and illustrated User Guide that 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.

Purchasing Westbay Traffic Calculators

All major credit cards accepted

Westbay Traffic Calculators, which comprises the four calculators described above, costs 98 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 ExcelThis is an Add-In for Microsoft Excel version 97 or higher (32 bit and 64 bit) that allows Erlang B and Erlang C functions to be included in your own spreadsheets.

Transactions are with Westbay Engineers Ltd. and are handled on our secure server.  You can have the software running on your PC five minutes from now!

Please choose a licence type

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.
A single user licence allows you to install the software on one PC.
Click here to purchase a single user licence ($98.00)
A site licence allows you to install the software on any PCs in one building, owned by the licensed company.
Click here to purchase a site licence ($495.00)
A global licence allows you to install the software on any of your company's PCs throughout the world.
Click here to purchase a global licence ($995.00)
Alternatively, if you would prefer to pay by cheque or money wire, please contact us.

Need more information?

Try looking in the FAQ (Frequently Asked Questions). Someone else may already have asked the same question.   Failing that, please send us an email.

Technical Specification

  Erlang B / Ext. Erlang B Erlang C Call Minutes
Operating system All 32 and 64 bit versions of Microsoft Windows.
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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Last modified: 29 April 2014

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