A Guide to Determining Call Center Staffing Needs
Illustration by Thomas Knapp

There are three foundational building blocks that need to be optimized to consistently deliver engaging customer experiences over the phone: people, processes and leadership. Our ongoing article series, “How to Deliver Engaging Customer Experiences,” published in Contact Center Pipeline magazine, covers each of these focus areas in detail. This guest post, a stand-alone from our series, will tackle how to calculate the number of agents needed to staff your call center.

After a few rewrites, we decided against publishing a dry, basic overview of these topics that would ultimately become a really good sleeping aid (we apologize to those already dozing off). As a result, and for your entertainment pleasure, we’ve written this article in dialogue format between a senior leader and their direct report (call center Grand Poobah); a dialogue you’ve likely encountered or will at some point in your career.

An Entertaining Dialogue Between a Call Center Leader and His Boss

CC Manager: Boss, we need to hire additional agents to properly staff our call center for 2017.

Executive [shaking his head thinking, not this again… but trying to be open minded]: What made you come to this conclusion?

CC Manager: We aren’t reaching our target service levels.

Executive [in a stern voice]: I admit I don’t know much about our target service levels, but we have 10 agents and each agent takes about 50 calls a day. If each call is six minutes in length, that’s five hours of work per agent. What the hell are agents doing for the other three hours?

CC Manager: It isn’t that simple, boss. For starters, calls come in randomly—not sequential. Therefore, you can’t calculate staff that easily.

Executive [being sarcastic]: Why don’t we tell customers to call at certain times so we can save them money in the long run?

CC Manager: Let’s look at the impact of being short-staffed from the agent’s perspective. For starters, being that the agent sees calls in the queue, he or she will then attempt to get through calls as quick as possible so that customers don’t have to wait. Consequently, not everyone will receive the “WOW” service we are wanting to deliver.

CC Manager: There’s more… Some of those customers, at least those who don’t abandon after waiting awhile, won’t be in the brightest of spirits when they finally reach a live agent.

Executive [being somewhat sarcastic]: We should play relaxing music while on hold.

CC Manager: Good idea, but there’s more. Let’s assume all callers patiently waited and ultimately reached a live representative and, after their call, received a survey. What are the odds your agent will score really well on all surveys?

Executive: Probably will have some score slightly above average, which isn’t what we want.

CC Manager: Exactly. And what if, during that same time period, one of the various systems our agent had to log into was down and, consequently couldn’t resolve a customer issue? Not all customers are forgiving you know…

Executive: Damn systems!

CC Manager: The potential long-term impact, should this trend continue, is that our agent’s morale suffers due to issues they couldn’t control. Then they start coming to work late, take longer breaks, etc. Along the way, we’ll also upset some customers—even lose a few. Now multiply this by a much larger volume of calls and you see how critical it is to allocate enough resources at the right time—especially important since people are our biggest expense.

Executive: OK. I get it. But how do we ensure that we aren’t over-hiring? Other executives already view this department as a cost center.

CC Manager: Well, they are wrong. This department is building our company’s brand. Why do you keep throwing money at retail stores when we interact with the most customers—more than any other store? Anyhow, before I get into staffing models, I wanted to let you know that I’ve forecasted call volume based on a three-year history of calls and took into consideration upcoming marketing campaigns, system maintenance and our online banking conversion. I have forecasts down to 30-minute increments. So I’m not just pulling numbers out of thin air.

Executive: How accurate is this forecast? Hopefully more accurate than our local weather man!

CC Manager: Well, its impossible to be 100% accurate, but we shouldn’t be off by more than 5%. Lets get into Erlang C.

Executive: [with a smirk]: Is he the brother of the guy who developed Hi-C?

CC Manager: Don’t quit your day job, boss.

CC Manager: Erlang C is a model developed in 1971, by A.K. Erlang. He was a Danish mathematician and engineer who invented the fields of traffic engineering and queuing theory—more specifically a solution to the problem of how many phone operators were needed to handle a given volume of calls. Most call centers use this—or variations of the model—to determine staff and scheduling.

CC Manager: While it’s not a perfect model, because it tends to slightly overestimate staff (one reason is that it does not assume any abandoned calls), it’s still a widely used model. In fact, many workforce management/planning solutions even use the model with variations to make it more real-world applicable. Worst-case scenario is that we are at least basing our assumptions on a model rather than just randomly guessing.

Executive: So how does it work?

CC Manager: Well, one approach is to use an online model and plug in key inputs, and the model will output the information we’re looking for. To do this, there are a few things we need to know.

CC Manager: First, our service levels. A service level is a measure used to refer to our team’s responsiveness to customers. Specifically, the percentage of calls we strive to answer in a matter of seconds. While no industry standards exist, it’s most common for call center service levels to be 80/20; meaning the goal is to answer 80% of the calls within 20 seconds. Our service level is 85/15.

Executive: How did we determine that?

CC Manager: There are many approaches (not one right answer) to do this. The approach we took was surveying our customers about their expectations. Other call centers sometimes determine service levels by benchmarking financial institutions similar to them. Others may use a quick rule of thumb based on the tolerance they have for abandon call rates (everybody defines these differently too). Typically, the higher your service level the lower the abandoned rate. For example, if you consistently reach 85/15 or in that range, your abandoned call rate will typically be in the 1% to 2% range. 80/30 ranges typically see an abandonment rate of 3% to 4% and so on.

Executive: This is getting complicated. What else do we need to know?”

CC Manager: Average talk time is another input. This is simply the average duration of each phone call our agents make. And is where effective training and efficient systems are so important. The quicker agents can diagnose the problem and navigate through, (often several) systems, the more time they have to build rapport with customers.

Executive: Is there more?

CC Manager: Yes. Another input is average handle time.

Executive: Let me guess. This is the amount of time for the entire call.

CC Manager: Close. This is the overall amount of time that is needed to answer a call and includes everything from inputting notes into our system to completing paperwork (after-call work)—basically whatever is needed to complete the transaction.

Executive: Doesn’t this pull people off the phones?

CC Manager: Yes. It’s impossible to eliminate. However, we can do a lot more to minimize after-call work. Streamlining processes will help ensure that we aren’t overstaffing.

Executive: I’m all ears!

CC Manager: This is where journey-mapping and process improvement come into play. A good exercise is to staple yourself to a common transaction and walk through the entire process. Then figure out how to streamline the process and create a better overall customer experience. Basically, we need to do this for the most common calls that come in through the call center (there are a bunch of them). Mapping all this out will also expedite the learning curve for new-hires.

Executive: Sounds like a lot of work. Do we have the bandwidth?

CC Manager: It is a lot of work. That’s why I think we should hire a consultant to help us—at least with the first few journey maps since it’s very time consuming. I know of a company, Blueprint Interactions. Doing this can also help reduce friction between frontline and support areas since they’ll be more aligned. But I digress…

CC Manager: You also need to know your call volume, ideally within 30-minute increments to be accurate.

Executive: Now can we plug into the model?

CC Manager: Yes. However, what the model outputs is just the start. There’s also the issue of shrinkage.

Executive: [looking around to make sure there are no HR folks]: Sounds horrible. Nobody likes shrinkage.

CC Manager: Shrinkage (or Rostered Staff Factor) is a measure of how much time your agents are spending off the phones due to paid lunches and breaks time off, meetings, training, etc.

Executive: We allow too many breaks. When I was your age, we never took any.

CC Manager: As I was saying… calculating shrinkage provides call centers with the minimum staff needed to schedule over and above the base staff to achieve desired service levels. Here’s how you would typically measure shrinkage…

CC Manager: In sum, Erlang C and shrinkage can help us determine staff.

Executive: [dozing off]: Sure I get it.

Well that concludes our post. We hope you enjoyed it and look forward to our next article in our series (in the September 2016 issue of Pipeline) on how to drive employee engagement.

Bill Stavros

Bill Stavros is Founder & CEO of Blueprint Interactions, LLC. He is also a Certified Customer Experience Professional (CCXP) through the CCXA.
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