Contact Center Trends

How to Calculate Call Center Service Level (SLA)

By Shauna Geraghty

0 min read

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The Importance of Contact Center SLAs

When call center service level is carefully defined and measured consistently over time, it can be used to make data-driven decisions that can have a positive influence on your company (which is why we recently launched a 100% Uptime SLA for our customers). In this blog, we outline step-by-step instructions to help guide you through this process.

1. Decide how you’ll classify abandoned calls

Deciding how you will classify abandoned calls is crucial to ensuring that service level is accurately assessing what you would like it to. There are three ways to classify abandoned calls:

i. Missed opportunities:

In this method of calculating service level, abandoned calls are considered missed opportunities to connect with a valued customer. Thus, they will negatively impact service level. This method of calculating service level is most common with companies that maintain a customer-centric approach, value customer service, and generate revenue from sales calls.

ii. Counted:

In this method, callers that hang up before the predefined time threshold will be counted as a “call offered” and will positively influence the service level calculation. This method is common within adequately staffed call centers with short wait times. These companies assume that abandoned calls are unavoidable and since their wait times are low, they can assume that an abandoned call is not due to an angry customer but rather a customer that was busy or lost cell phone service and will call back. Thus, these calls should not negatively impact the service level calculation.

iii. Ignored:

This approach assumes that abandoned calls are unavoidable and thus should not be considered in the service level calculation. Thus, these calls do not affect service level, either negatively or positively. This method takes a more general approach to exclude calls that were both abandoned while waiting for less time than the service level threshold and more time than the service level threshold.

2. Define a formula

After you have decided how to classify abandoned calls, you should define a service level formula, based on this classification. This is essential to ensuring that service level is measured consistently over time. A few examples of call center service level formulas are as follows:

3. Decide on a time interval

Deciding on a time interval is crucial and will significantly influence your service level calculation. When deciding on a service level threshold, you should consider all (or most) of the factors listed in our “Selecting a Service Level Objective” post.

4. Decide when the time interval starts

After you have chosen a time interval, you should define when it starts. Some suggestions are:

  • When the caller selects their final option in the IVR
  • When the call enters the ACD for a specific agent or department
  • After the waiting queue greeting has ended
  • After a predetermined time interval (i.e. 5 seconds after the caller enters the queue)
  • As soon as the phone rings

5. Decide on a service level objective

Once you have defined your service level and time interval, you are ready to select a service level objective. Again it is important that you do so with the domains listed in the “Selecting a Service Level Objective” in mind.

6. Decide on a measurement interval

Once you have selected your service level objective, you can now decide on the measurement interval. Some call centers are constantly measuring (i.e. each 15 seconds, minute, 10 minutes, 30 minutes or hour) in order to adjust their staffing accordingly. These call centers will have a more accurate assessment of service level as the day progresses. Other call centers prefer to assess the service level of the past week, just to ensure that they are meeting their goals. This type of measurement approach is helpful for call centers that don’t make timely staffing decisions based on service level, but rather use it as a rough estimate of performance for the past week.

Of course, the longer the measurement interval, the more difficult it can become to pinpoint periods of problematic service levels. It is therefore essential that careful consideration should be taken when selecting a measurement interval.

7. Decide which team, agent and department to collect data from

Some call centers are only interested in the service levels of a certain department (i.e. customer support) whereas others would like to analyze service levels across the company as a whole, as well as for each department, team and agent in order to better understand how their company is performing. Of course, these may change over time, depending on your company’s needs.

8. Decide how to collect the data

Call center software that allows you to accurately measure service level in a way that is meaningful to you is crucial. Most ACDs will collect data based on the number of calls that had a service level event within your predefined time period:

  • The call is answered
  • The call is abandoned
  • The caller waits longer than the predefined service level threshold without hanging up or being answered

After you decide how to classify abandoned calls, you can better understand how to account for each call type in your service level calculation.

9. Analyze the data

Many call center software solutions will automatically analyze service level for the predetermined time period you selected. This makes tracking service level as simple as opening that tab on your software.

10. Display the results

Agents and managers can only make data-driven decisions based on service level metrics when they have access to that data in real-time. Make the results visible by displaying them on agent dashboards, on TV monitors within your call center and within daily feedback reports for maximum impact.

11. Act on the results

Data is useless unless it is used to make decisions that will help you reach your goals. As you monitor service level, make decisions based on this data. Route overflow calls to at-home agents, ask in-house agents to work late during a rush and plan agent breaks so that service level isn’t compromised. These are all simple examples to help you improve service levels when they are declining.

12. Repeat the process

Companies are fluid and so should their service level objectives. It is important that you are constantly reassessing your customer’s needs and expectations as well as whether or not service level objectives are in line with your company values and business goals. Adapting overtime is essential to this process.

Following the 12 aforementioned steps will help you measure your service level accurately and consistently. You can also check out this blog post for common causes of low service level.

2021 Talkdesk Global Contact Center Kpi Benchmarking Report

2021 global Talkdesk contact center KPI benchmarking report

Download now to learn more about:

  • The importance and benefits of benchmarking.
  • How contact center metrics changed during 2020 compared to 2019.
  • How your contact center performance stacks up against peers across industries, regions, and company sizes.
  • Tips to optimize your contact center and improve CX.


Shauna Geraghty

As the first U.S. employee, Shauna helped to scale Talkdesk to over 1,000 employees in 7 offices globally. During her tenure, she has built Talkdesk's Marketing, Talent and HR functions from the ground up. Shauna has a doctorate in clinical psychology and has applied foundational knowledge from the field of psychology to help propel Talkdesk along its hyper-growth trajectory.