Руководство По Проектированию для Cisco Cisco Customer Response Solution Downloads

 illustrates the principal steps and design considerations for sizing a call center.

 is a general overview of the design considerations for call sizing. For a detailed description 

of the call center sizing design process, refer to the section on sizing call center resources in the Cisco 
IP Contact Center Solution Reference Network Design Guide, available online at 

There are similar basic call center sizing considerations and steps for IPCC Enterprise, and they also can 
be used in sizing a smaller contact center for IPCC Express. This call sizing approach will provide you 
with the minimum number of IVR ports to support the total BHCA.

In addition, you should include the following design considerations, specific to IPCC Express, in your 
call center sizing calculations:

At a minimum, plan on enough capacity to replace your existing system. The replacement system 
should perform at least as well as the one it is replacing.

All call center designs must be sized to the system correctly. Do not size a call center without using 
the IPCC Express Configuration and Ordering Tool to determine the required quantity of servers and 
gateway trunks.

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IP

 C

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 C

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in

g

BHCA Seen at

Queue Ports

Average Queue

Time (AQT)

Busy Hour Traffic

(BHT) In Erlangs

% Blockage

(Grade Of

Service)

Avg. queue duration
from ErlangC
calculator

BHT=(BHCA * AQT

seconds)/3600 (for all\
duration types)

BHT = (BHCA * AQT

seconds/3600 (for all
duration types)

% Blockage

(Grade Of

Service)

BHCA seen at

IVR ports

Erlang Load on

IVR port.

Call Center

INPUT

Call Center

OUTPUT

BHT=(BHCA * IVR Port Time)/3600

% calls blocked when no ports
available( lowest % possible)

Busy Hour Traffic=(BHCA * AHTsec)/3600

(Erlangs)

% Blockage = 0.01 (1%  for PSTN Trunks)

    =   0.001 (0.1% for IVR Ports)

# IVR

 Ports for

P&C

BHCA (T): Total Busy

Hour Call Attempts

Use Erlang C Calculator

Use Erlang B Calculator

Use Erlang B Calculator

# Agents

# IVR

Ports for

Q’ing

Queued

Calls

(%)

Avg. Q-Time

Total #

IVR

PORTS

Average Hold

time for IVR Port

Includes Prompt Playout/
Menu Navigation(if any)

Size IPCC

Express

Agents

Size IVR Ports 

for Queueing

Size IVR

Ports

AHT for call

treatment

BHCA for call

treatment

BHCA (T)

AHT (secs)

Service Level

Goal (% in secs)