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Erlang add-ins for Excel to allow erlang traffic calculations to be included in excel spreadsheets

Erlang for Excel ™ is an Add-In that introduces eight Erlang B and Erlang C functions into Microsoft Excel.   These functions can be used in spreadsheets in the same way as regular functions and allow you to build your own traffic and call center Excel workbooks.

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Introduction to Erlang for Excel ™

Erlang for Excel is included free with every copy of Westbay Traffic Calculators.  It is an Add-In for Microsoft Excel 97 or higher, which introduces eight new functions to Excel, allowing you to incorporate Erlang B, Extended Erlang B and Erlang C calculations in your own spreadsheets.  Erlang for Excel supports both the 32 bit and 64 bit versions of Excel.

These functions assist in estimating the number of telecommunications lines required to make up a trunk group; to analyse the performance of an existing trunk group and to estimate the number of call center agents required at an inbound call centre.

"I recommend this product highly"
Computer Telephony Magazine

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

Erlang for Excel is included as a package with Westbay Traffic Calculators, which is available for 98 US Dollars.   Click here to find out how to purchase.

Using Erlang for Excel ™

Erlang for Excel brings eight additional functions to Excel 97 or higher spreadsheets.  They allow you to perform Erlang B calculations within your own spreadsheets.   The calculations work up to 90,000 Erlangs / Lines!

Erlang for Excel

This picture shows and example of one of the Erlang B Add-In functions in use.   The right hand column shows the results of calculations using the ErlBLines() function to work out how many lines are required to carry the busy hour traffic that has been entered in the left hand column.

The eight functions which the Add-In offers are:

* Extended Erlang B examples have not been included below.  The functions are exactly the same as their Erlang B equivalent, except that they have an additional parameter for the recall factor.

ErlBLines()

This function is used to work out how many lines are required to meet given blocking (service level) targets, if the busy hour traffic and number of lines are known.  For example:

if the busy hour traffic is 100 Erlangs,
and the maximum acceptable blocking is 0.025 (2.5% of calls)

then the following formula will return the number of lines required (111).

=ErlBLines(100,0.025)

ErlBBlocking()

What blocking will be experienced?

This function is used to work out how much blocking would be experienced if the busy hour traffic and number of lines are known.  For example:

if the busy hour traffic is 1500 Erlangs,
and there are 1000 lines,

then the following formula will return the blocking encountered (0.335).

=ErlBBlocking(1500,1000)

ErlBTraffic()

How much traffic can a trunk group handle?

This function is used to work out how much traffic a trunk group can handle number of lines within that trunk group are known.  For example:

if the target blocking figure is 0.03 (3% of calls blocked)
and there are 200 lines,

then the following formula will return the busy hour traffic in Erlangs which the trunk group could handle (190.881).

=ErlBTraffic(0.030,200)

ErlCAgents()

How many agents does a call centre require?

This function is used to estimate the number of agents required at an inbound call center for given call volumes.  For example, to answer the following question:

if 3000 calls are received in a call center in one hour, and the average call duration is 300 seconds, how many agents are required if 85% of calls must be answered within 20 seconds?

then the following formula will return the number of agents required (263).

=ErlCAgents(3000,300,85,20)

ErlCCalls()

How many inbound calls can a call center handle?

This function is used to estimate the number of calls a call center can handle for a given number of agents.  For example, to answer the following question:

if 115 agents are available to handle inbound calls, and the average call duration is 250 seconds, how many calls can be handled agents if 80% of calls must be answered within 20 seconds?

then the following formula will return the number of calls that can be handled (1547).

=ErlCCalls(115,250,80,20)

Westbay Traffic Calculators

Erlang for Excel is packaged with Westbay Traffic Calculators.  Westbay Traffic Calculators includes four traffic engineering calculators in one programme, and selected using tabs. They assist in trunk group dimensioning and call centre staffing analysis. Historical reporting and printing is also included.


"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 2210

Documentation

Instructions for installing and using the Erlang for Excel Add-In are provided in a workbook that is installed with Westbay Traffic Calculators, and can be started using an option on the Start menu.

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.

Purchasing Erlang for Excel

All major credit cards accepted

Westbay Traffic Calculators, which comprises Erlang for Excel and the four calculators described above, costs 98 US Dollars for a single user licence.   You can pay using any major credit card or PayPal.

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!)

Erlang for Excel supports all versions of Microsoft Excel from Excel 97 onwards and including Excel 2010 (32 bit and 64 bit).

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
Excel requirement Excel 97 or higher (32 bit and 64 bit versions); Windows 95, 98, ME, NT4, 2000,  XP, Vista or Windows 7.
Traffic model used Erlang B / Ext. Erlang B Erlang C
Operational limits BHT 90,000 (max) Erlangs
Blocking 0.001 - 0.500
Lines 90,000 (max)
Retries 95% (max)
Agents 5000 (max)
Calls per hour 300000 (max)
Duration 3600 (max) seconds
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Last modified: 06 April 2014

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