Term Project – Call Center Operations
1
Term Project – Call Center Operations
SOM 686, Fall 2006
Darren Mitchell
Hayden Gilbert
Serge Suprun
Term Project – Call Center Operations
Agenda
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Overview
 Call Center Statistics (October), Definitions & Forecast
 Process View of the Call Center
 Call Center Competencies, Architecture, Three Key Measures
& Little’s Law
 Call Center Flow, Delays, Queues & Process Attributes
 Flow Rate-related Measures of Call Center Capacity
 Flow Time-related Measures of Customer Delay
 Inventory-related Measures of Customer Queues
 Performance Improvements & Managing Capacity

Term Project – Call Center Operations
Overview
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Time Warner Cable Los Angeles
– Bought Adelphia
– Exchanged properties with Comcast
– Now provides cable, internet & telephone services to over 2
million customers.
Time Warner Advanced support is local
– Teamed up with outsourced partner to provide basic support
for all three products.
Basic support includes: billing, basic repair, changes to the
accounts & general questions.
Outsourced partner provides basic support from 3 call center
locations: USA, Canada & Argentina.
Term Project – Call Center Operations
Overview
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Call Center in Argentina supports English & Spanish-speaking
customers.
There are 36 agents employed in the center
– 12 are Spanish only
– 24 are bilingual
On average, the call center handles 40,000 calls per month.
However, over last 2 months handled calls were 36.5% over
forecast.
Service level suffered over past 2 months too
– In October, only 32.4% of calls were answered within
appropriate time limit.
Term Project – Call Center Operations
Call Center Statistics (October) and Definitions
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DATE
FCAST
NCO
% O/U
FCAST
ABA
SVL%
ABA%
ASA
(Seconds)
Hold
(seconds)
Hand
(seconds)
10/1/2006
952
1,385
45.5%
595
12.9%
43.0%
664
82
510
10/2/2006
1,473
1,877
27.4%
560
14.0%
29.8%
481
90
500
10/3/2006
1,362
1,688
23.9%
241
31.8%
14.3%
205
86
489
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10/30/2006
1,473
2,008
36.3%
386
38.1%
19.2%
285
75
476
10/31/2006
1,263
2,237
77.1%
238
46.5%
10.6%
156
73
447
41,168
54,494
32.4%
11,118
37.7%
20.4%
241
74
462
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NCO – number of calls offered
ABA – number of calls abandoned; ABA% - percentage of calls abandoned
SVL – service level
ASA – average speed of answer
Hand – average handle time
Term Project – Call Center Operations
Forecast
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Past 2 months, Argentina used naïve forecast:
– (Based on the last year historical data)
– Forecast didn’t take into the account recent product changes &
integration projects
– As a result  October call volume was 32.4% over forecast.
We are suggesting to use Moving average forecast.
Ex:
 MA103 = (A10+ A9+ A8)/3, using last months data is
(54,494+56,221+50,221)/3=53,636
 Therefore, F11=53,636. November forecast should be for 53,636 calls.
This would allow Argentina to staff appropriately.
Term Project – Call Center Operations
Process View of the Call Center
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Process
Inputs
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Outputs
Inputs/Outputs – customers calling for service/customers completed the call
Flow Units – customers
Network of Activities and Buffers – answering customers’ calls
Resources – customer service agents (CSA), phone automated system
(PAS), etc.
Information Structure – account management system, reference materials,
etc.
Term Project – Call Center Operations
Call Center Competencies and Architecture
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4 Dimensions for measuring the competence of the call center:
– Process Cost
– Process Flow Time
– Process Flexibility
– Process Quality.
Argentina call center focuses on the low cost.
– Call center provides high-quality Spanish support.
Argentina call center process architecture is defined by the types of
resources (CSA, PAS, etc).
– Call center falls somewhere along the spectrum between two extremes
(flow shop and job shop).
– Flow shop fits better, as call center uses specialized resources that
perform limited tasks & produce large volumes with high precision and
speed.
Term Project – Call Center Operations
Three Key Call Center Measures
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Flow Time = Time Customer spends:
– In automated phone system
– Waiting in the queue for an agent
– Talking to an agent.
Ex: October Average PAS time is 46, Queue average waiting time is 32 &
handle time is 462 seconds.
T=540 seconds

Flow Rate = Number of customers that flow through a specific point in the
call center process per unit of time.
 Inventory = Total number of customers present within call center
boundaries.
Ex: Argentina call center is 24/7 & call patterns are very different.
Therefore, to simplify calculations we will use I=27 customers
Term Project – Call Center Operations
Little’s Law
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Throughput = Average number of customers that flow through the call
center per unit of time.
Little’s Law - Average inventory (=) Throughput (x) Average flow time.
– I=RxT
Ex:
We identified:
T = 540 seconds (9 min)
I = 27 customers.
Therefore, R = I/T
R = 27/9
R = 3 customers/minute
Term Project – Call Center Operations
Call Center Flow, Delays and Queues
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Capacity
Rp = c/Tp
Customer
Arrival Rate
Throughput
Ri
R = Min (Ri, Rp)
Number:
Ii
+
Ip
=I
Time:
Ti
+
Tp
=T
In:
Customer
Queue + Service =Process
Term Project – Call Center Operations
Call Center Process Attributes
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
Inflow Rate Ri = Average rate of customer arrivals per unit time.
– In the Argentinean call center, Ri = 5 customers/minute
Processing Time Tp = Average time required by agent to process the customer.
– Tp = 462 (agent) + 46 (PAS) = 508 seconds
 c = Number of agents in the resource pool
– c = 36 agents in Argentina
 Process capacity (Rp) = Total processing rate at which customers are
processed by agents in the resource pool.
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– Rp = c/Tp or Rp = 36/8.47 = 4.25 customers/minute
Buffer capacity (K) = Maximum number of customers that can wait in
queue.
– K = 120 (there are 10 lines that can hold 12 each at any given time)
Term Project – Call Center Operations
Flow Rate-related Measures of Call Center Capacity
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Throughput rate (R) = Average rate at which customers flow through the
call center process
– R = min (Ri, Rp)
– In our case, Rp is smaller, so R = Rp = 4.25
Capacity utilization (ρ) = Average fraction of the resource pool capacity that
is occupied in processing customers
– ρ = R/Rp
– In our case, R = Rp and ρ = 1
» Our resource pool is constantly busy processing customers.
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Safety capacity (Rs) = Excess processing capacity available to handle the
customers inflows.
– Rs = Rp – Ri
– In our case, Rs = 4.25 – 5 = -0.75
» All the available capacity is busy processing arrivals.
Term Project – Call Center Operations
Flow Time-related Measures of Customer Delay
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Average waiting time (Ti) = Time that a customer spends in
queue.
– Ti = 32 seconds.
Average theoretical time = Average processing time of a
customer.
– Tp = 462 seconds + 46 seconds (automated system) = 508
seconds
Average flow time in the process (T) = Average time that a
customer spends waiting in queue & being served
– T = Ti + Tp or T
– 508 + 32 = 540 seconds or 9 minutes
Flow time efficiency = Proportion of time that a customer
spends being served rather than waiting in queue
– Tp / T = .94
Term Project – Call Center Operations
Inventory-related Measures of Customer Queues
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Average queue length = Average number of customers waiting
for service
– Ii = R x Ti
– Ii = 4.25 x 0.53 = 2.25 customers waiting for service
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Average number of customers in service = Average in-process
inventory
– Ip = R x Tp
– Ip = 4.25 x 8.47 = 35.99 customers in service
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Average total number of customers in the process
– I = I i + Ip
– I = 2.25 + 35.99 = 38.24 customers in the process
Term Project – Call Center Operations
Call Center Flow, Delays and Queues
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Capacity
Rp = c/Tp
Arrival Rate
Throughput
Customer
5 customers/min
Customer
4.25 customers/min
Number:
2.25
+
35.99
= 38.24
Time:
508
+
32
= 540 seconds
In:
Queue +
Service = Process
Term Project – Call Center Operations
Performance Improvements
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The following levers improved process performance:
 Decrease variability in customer interarrival & processing
times.
 Decrease capacity utilization (or increase safety capacity)
either by
– Decreasing the arrival rate or increasing the unit processing
rate
– Increasing the number of servers
 Synchronize the available capacity with demand.
Term Project – Call Center Operations
Managing Capacity
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Capacity utilization (ρ = Ri/Rp ) can be reduced by increasing
average processing rate (Rp)
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In order to increase processing rate (Rp = c/Tp) we
recommended decreasing average processing time (Tp)
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To achieve a decrease in processing time:
– Identified that billing & escalated calls took longer to
handle in this call center vs. similar centers.
– Thus recommended & implemented 2 separate hour
training segments
» Billing prorates explanation
» How to handle escalated calls
Term Project – Call Center Operations
Call Center Statistics (November)
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DATE
FCAST
NCO
% O/U
FCAST
ABA
SVL%
ABA%
ASA
Hold
Hand
11/1/2006
1,973
2,093
6.08%
268
47.3%
12.8%
167
66
449
11/2/2006
1,986
2,022
1.81%
266
54.7%
13.2%
152
62
425
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11/25/2006
1,368
1,513
10.60%
279
56.5%
18.4%
139
48
370
45,381
47,832
5.40%
7,080
52.1%
14.8%
153
58
410
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Processing time decreased to 410 seconds
– Tp = 410+46 = 456 seconds or 7.6 minutes
Process capacity Rp = c/Tp or Rp = 36/456 = 4.74 customers/minute
Result: Capacity Utilization ρ = Ri/Rp or 5/4.74 = 1.06
Term Project – Call Center Operations
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