Cisco Cisco IPCC Web Option Leaflet
9-6
Cisco Unified Contact Center Enterprise 7.5 SRND
Chapter 9 Sizing Call Center Resources
Erlang Calculators as Design Tools
–
Unified CVP ports and servers — Refer to the Cisco Unified Customer Voice Portal Solution
Reference Network Design (SRND), available at:
Reference Network Design (SRND), available at:
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Gateways — Refer to the Cisco Unified Customer Voice Portal Solution Reference Network
Design (SRND), available at:
Design (SRND), available at:
Erlang Calculators as Design Tools
Many traffic models are available for sizing telephony systems and resources. Choosing the right model
depends on three main factors:
depends on three main factors:
•
Traffic source characteristics (finite or infinite)
•
How lost calls are handled (cleared, held, delayed)
•
Call arrival patterns (random, smooth, peaked)
For purposes of this document, there are mainly two traffic models that are commonly used in sizing call
center resources, Erlang-B and Erlang-C. There are many other resources on the internet that give
detailed explanations of the various models (search using traffic engineering).
center resources, Erlang-B and Erlang-C. There are many other resources on the internet that give
detailed explanations of the various models (search using traffic engineering).
Erlang calculators are designed to help answer the following questions:
•
How many PSTN trunks do I need?
•
How many agents do I need?
•
How many IVR ports do I need?
Before you can answer these basic questions, you must have the following minimum set of information
that is used as input to these calculators:
that is used as input to these calculators:
•
The busy hour call attempts (BHCA)
•
Average handle time (AHT) for each of the resources
•
Service level (percentage of calls that are answered within x seconds)
•
Grade of service, or percent blockage, desired for PSTN trunks and Unified IP IVR ports
The remaining sections of this chapter help explain the differences between the Erlang-B and Erlang-C
traffic models in simple terms, and they list which model to use for sizing the specific call center
resource (agents, gateway ports, and Unified IP IVR ports). There are various web sites that provide call
center sizing tools free of charge (some offer feature-rich versions for purchase), but they all use the two
basic traffic models, Erlang-B and Erlang-C. Cisco does not endorse any particular vendor product; it is
up to the customer to choose which tool suits their needs. The input required for any of the tools, and
the methodology used, are the same regardless of the tool itself.
traffic models in simple terms, and they list which model to use for sizing the specific call center
resource (agents, gateway ports, and Unified IP IVR ports). There are various web sites that provide call
center sizing tools free of charge (some offer feature-rich versions for purchase), but they all use the two
basic traffic models, Erlang-B and Erlang-C. Cisco does not endorse any particular vendor product; it is
up to the customer to choose which tool suits their needs. The input required for any of the tools, and
the methodology used, are the same regardless of the tool itself.
Cisco has chosen to develop its own telephony sizing tool, called Cisco Unified CCE Resource
Calculator. The version discussed here is designed to size call center resources. Basic examples are
included later in this chapter to show how to use the Cisco Unified CCE Resource Calculator. Additional
examples are also included to show how to use the tool when some, but not all, of the input fields are
known or available.
Calculator. The version discussed here is designed to size call center resources. Basic examples are
included later in this chapter to show how to use the Cisco Unified CCE Resource Calculator. Additional
examples are also included to show how to use the tool when some, but not all, of the input fields are
known or available.
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