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How to Avoid Abandoned Calls in Contact Center

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How high call volume and high abandon rates affect contact centers


The eruption of Iceland’s Mount Eyjafjallajokul in April 2010 disrupted air traffic across Europe, stranding thousands of passengers. Scrambling for alternatives, passengers flooded airline, train, car rental, travel agency, and hotel contact centers with calls. Hold times

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How high call volume and high abandon rates affect contact centers


The eruption of Iceland’s Mount Eyjafjallajokul in April 2010 disrupted air traffic across Europe, stranding thousands of passengers. Scrambling for alternatives, passengers flooded airline, train, car rental, travel agency, and hotel contact centers with calls. Hold times were frequently in excess of 30 minutes. Agents were under tremendous stress as they fervently attempted to find viable solutions for haggard and angry customers. Customers, in turn, were bouncing from one contact center to another in hopes of getting through and finding a way home.

In December 2009, heavy snowfall across the East Coast of the United States caused an unexpected influx of calls to ski resorts from Virginia to Maine. Some resorts reported call volume increases exceeding 65 percent.

During the holiday season, the Figi contact center volume increases 10,000 times. To accommodate this sudden increase in calls, the company expands the contact center staff from 100 to 1,200 agents.

All contact centers deal with periods of high call volume. Whether because of expected events, such as seasonal holiday sales, or due to unexpected events, like volcanic eruptions, significant call volume increases can adversely influence the contact center, and the company, if not handled appropriately.

This white paper explores, through three case studies, the challenges contact centers experience stemming from high call volume. It presents the ramifications of high volume spikes on the company’s bottom line, its customer loyalty, and agent satisfaction. The paper also details solutions contact centers can use to effectively deal with expected and unexpected volume spikes, and provides examples of companies that successfully manage what could be the most common problem in call centers.

High volume and abandon rate

Call volume is rarely consistent all the time, and all contact centers experience spikes in call volume beyond what their staff can normally handle. Even contact centers with excellent forecasts and proper schedules experience periods where staffing cannot match volume. Furthermore, because contact centers are typically under pressure to do more with less, many have decreased the number of agents available to answer calls. The combination of increased volumes and decreased staff will inevitably lengthen the amount of time customers spend on hold. Customers are patient to a point, but everyone has their limit. When wait time reaches a personal threshold, the customer usually abandons the call.

An abandoned call is one where the caller disconnects while on hold, waiting for an agent. The abandoned rate is the ratio of abandoned calls to the total calls received. Call volumes and abandoned rates go hand-in-hand. As the call volume increases, the abandon rate may also increase.

While there is no industry best practice when it comes to abandoned calls, over the years contact centers have determined the optimum abandoned rate is between 3 percent and 5 percent. Moreover, callers do not hang up according to a linear function. Abandoned calls follow more of a parabolic function, with more than 50 percent of the abandons occurring within the first 15 seconds customers are on hold (see Figure 1).

The number of abandoned calls experienced by a call center is a function of the number of agents, the call volume, and the caller’s willingness to stay on hold. The numbers of agents and call volume effects the time customers will stay on hold. While the number of agents stays relatively constant, call volumes vary greatly. If the volume increases significantly, it may eventually reach a point where the number of incoming calls outstrips the agents’ capacity to answer calls and all new calls are placed on hold (Figure 2). The further the volume climbs away from that point, the longer the hold time becomes and the the possibility that customers will hang up increases.

Customers who abandon a call have two options:

For the contact center neither is a desirable option, because they either miss potential revenue or place agents under additional stress and eventually affect customer satisfaction. High volumes and increased abandon rates are a lose/lose situation for contact centers.

3. Cost of abandoned calls

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Abandoned calls are missed opportunities. For each caller who hangs up, there is a possibility that he or she may contact a competitor. Under normal circumstances, the probability is small. However, the higher the abandon rate climbs, so does the rate at which customers leave. The following two figures show how a high abandon rate can affect a company’s bottom line. Figure 3 shows the number of abandoned calls related to the call volume of contact centers with 50 agents, a service level of 80 percent of calls answered in 30 seconds, and where the average handle time is 7½ minutes.

In Figure 3, the Call Capacity line indicates the maximum number of calls the agents can handle based on the assumptions listed above. Notice that once the call volume rises above the call capacity, the number of abandoned calls increases as a percentage of the total call volume. The effect is that many of those callers likely will venture to a competitor and take their purchasing dollars with them. If this was an uncommon occurrence, then the impact to the company may not be severe. However, if call volume spikes are common or if the contact center typically runs at more than a 5 percent abandon rate, then the higher volumes will have a much more significant impact on the company’s bottom line.

The following table shows the potential cost of abandoned calls, based on the assumption that 35 percent of those who disconnect contact a competitor and the average sale is $50. This contact center could lose almost $20,000 in a single hour, during periods of high call volume.

This example shows that even small and short spikes in call volume can have a large impact on a company’s bottom line. A similar outcome may occur if fewer agents were on the phone due to a snowstorm or technical problems. In either case, a dramatic increase in the abandon rate may have an equally dramatic impact on revenues.

The agent satisfaction/abandon rate correlation

In organizations where there are no alternatives, such as government offices or public utilities, high volumes and increased abandon rates will actually increase call volume. Customers who do not wish to stay on hold will simply hang up and call again at another time (see Figure 5). While customers may call retailers back, there is a greater possibility that they simply find another vendor. However, in situations where there is no substitute, customers simply call the contact center two or more times.

The following table (Figure 6) depicts how this practice of calling organizations multiple times can affect a contact center’s call volume. Using the same 50-agent contact center and the same assumptions, the table shows a real increase in call volume.

Under normal circumstances, contact center agents have a few seconds between calls to recover and reset. However, during times of high call volumes, this gap decreases significantly and can disappear altogether. Without the gap between calls, the stress level of the agent increases. Few agents can take calls continually for two, three, or more hours without an adverse effect on how they interact with customers.

High volumes also have the potential of reducing customer patience. After hanging on a call where they were on hold for several minutes or calling multiple times, a customer is impatient, upset, and not typically in a mood to give the agents a break. If issues are not resolved quickly, the agents can (and most likely will) be the focus of customer frustrations. While agents are trained not to take the comments personally, there is a limit to what training can do and eventually the agents will become noticeably stressed, adversely affecting their interactions with future customers and potentially increasing agent turnover.

As mentioned, all contact centers experience periods of high volume. If these spikes are anomalies, then their effects on the agents is minimal. However, long periods of high volume or increased hold times can have a real affect on agent morale. Agent moral does have an impact on a company’s bottom line. In some studies it has been revealed that as little as a 1 percent decrease in agent moral can have a 2 percent decrease on customer satisfaction. In addition, high volume contact centers with a high agent turnover rate, also has increased training costs and decreased overall center efficiency.


Since high volume spikes are a normal part of contact center operations, most contact centers can prepare for when they do occur. Many times, volume increase occurs at predictable times, such as holiday seasons, new product releases or software upgrades, and accurately predicted weather events. However, many times spikes are unexpected, such as unforeseen weather events, public infrastructure failures, or unknown issues in a new software upgrade. In the past, contact centers have scrambled for additional agents by “borrowing” ex-agents from other departments. In cases of predicted adverse weather, it is not an uncommon practice for contact center management to reserve rooms at a local hotel for key agents and supervisors who are expected to cover the center for the duration of the weather condition.

Today, the technological spectrum available to contact centers allows a much wider variety of solutions. The type of call spikes and the contact center’s business model determines which technological solution is the best fit. In addition, some time-tested methods are still valid, but can be enhanced by new technology.

Call avoidance

One traditional method of handling call spikes has been to avoid calls by alerting the caller about a long waiting period. Many contact centers place a message of the day on the IVR indicating they are experiencing a period of high call volume. Some contact centers include an estimated answer time. For example, a local telephone company’s voicemail system has become inaccessible so when a customer calls the technical support center, he or she may receive the following message:

“We are experiencing high call volume and we apologize for any inconvenience. The expected wait time is 10 minutes.”

Many contact centers have predictable peak times and most do not staff for peak volumes. In these cases, the contact center may inform the customer of the high call volume times, and offer a choice of times to call back, when call volume is expected to be much lower. For example, a caller to a local natural gas utility might hear the following during the last week of the month:

“Thank you for calling Blue Flame Gas Co-Op. All agents are helping other customers. We normally experience high call volumes between the 25th day of the month and the end of the month. If your issue is not critical, please call back after the first of the month.”

While these methods are still valid, contact centers now have additional options to control high volumes and avoid calls. Contact centers can offer callers a call back when their place in queue reaches an agent, or schedule a call back at a time of the customers’ choosing. The company’s customer service Web page can also be re-designed to offer customers the opportunity to schedule a call back.

Another option is to provide proactive communication between the call center and the customer. By alerting customers that there is an issue and providing periodic updates, contact centers can decrease the call volume into the center and maintain a reasonable wait time. For example, a local produce delivery company may decide to set up an outbound calling campaign to inform its customers of possible delays in deliveries due to flooding of a major highway. To contact the largest number of customers, businesses should use several communication channels, including telephone, email, SMS/Text, and social media.

Expected spikes

Many contact centers have predictable call volume increases. Retailers experience similar call volume patterns around the same time of the year. Other companies, such as software vendors, can expect a certain increase in call volume with every software release and update.

If the increase is small, for example in the area of 5 percent, or if the surge is expected to be very short (one to two days), it may be more effective for contact center managers to offer overtime to agents. Allowing agents to work the overtime from home or at an office closer to their homes may make the offer more palatable and therefore more appealing. Furthermore, by letting the agents work their entire shift from home or in a remote office, management decreases the possibility of gaps in coverage due to agents being caught in traffic or other unexpected events. IP-based contact center and communication solutions provide uncomplicated ways of connecting remote agents. In addition, the unified communication capabilities embedded in most applications, supply effective ways to pass information between agents and supervisors.

For short or low volume surges, contact centers may also borrow employees (typically ex-agents) from other departments. Modern IP-based communication solutions supply unified desktops that provide queue information, presence status, and multiple communication channels in a single interface. In many cases, back-office employees and contact center agents employ the same unified desktop. A unified desktop allows back-office workers to become contact center agents quickly and enables contact center managers to react to expected and unexpected spikes quickly and with greater call processing efficiency.

For longer-term, planned volume increases, many contact centers employ contract employees. Typically, contract employees answer rote questions and deal with straightforward issues (such as tracking packages, order entry, and refunds). Because these issues normally do not require assistance from more experienced or expert agents, contract employees are set up in remote locations or at home. IP-based solutions can direct telephone traffic to separate locations (creating redundancy) or into a single location then passed to multiple locations. In addition, a unified desktop with multiple solutions allows contract agents to ask for and receive assistance from experts or experienced agents through on-line presence and multiple communication channels.

The growth of at-home agents has been on the rise in recent years and many are hired as contract agents for seasonal employers. At-home agents can connect into a corporate network through a VPN or connect to a Web-based agent interface. IP-based solutions offer softphones that can be employed over a VPN. Other agents may choose to use regular analog telephones to receive calls. Finally, the video capability of many unified desktops supports effective training in a distributed environment.

Unexpected events

Unexpected call volume increases are the most damaging to customer satisfaction. These events are typically caused by emergencies like unforeseen product issues, infrastructure problems, or natural disasters. The contact center rarely has warning and needs to increase staff quickly. Messages of the day, overtime and borrowing agents are traditional methods of coping with volume spikes and are still used with great frequency and varying effectiveness.

With the capabilities of IP-based communication systems, contact centers have additional and more effective options. In the past, agents were called and asked to come into the center. Today’s technology allows agents to log into the contact center solution from their home, increasing the chances that agent activities will benefit the contact center and decreasing the lag time.

Unified desktops streamline the login process for borrowed employees. In the past, when contact centers borrowed employees from other departments, employees were required to physically move to the contact center, temporarily, until the high volume ebbed. This could be problematic if the center was on another floor or in another building. With a unified desktop, once the employee agrees to be an agent, the contact center manager assigns him or her to a queue on the fly, or simply asks the employee to logout and log back in as an agent.

Contact centers that require highly skilled agents, such as “ask a nurse” centers, may have part-time at-home agents on call to be used in case of high volumes. IP-based solutions let these at-home agents quickly log in to a contact center and immediately start taking calls. Finally, with advances in mobile applications, at-home agents do not have to be at home to answer calls. Calls can be transferred to a smartphone with an application installed. Opening the application connects the agent to the contact center solution, and the agent begins to receive calls remotely, thereby seamlessly relieving some of the high volume spike at the call center.

Risk mitigation

Most volume spikes are caused by events outside the contact center’s control. However, contact centers are not always at the whim of outrageous fortunes; they do have the responsibility for managing risks under their control. Every contact center should have a business continuity plan, in the event of local inclement weather, natural or manmade disasters, geo-political events, or technological problems.

Today, a broad spectrum of technological advances are available to contact centers, and offer a wide variety of solutions. Contact centers can continue to receive and answers calls in all but the most dire of circumstances. From unified desktops to geographically distributed contact centers, the best defense against inclement weather, volcanic eruptions, or a careless backhoe operator, is to diversify the locations of agents.

Distributed contact centers place agents at different physical locations and provide several advantages to a call center. By distributing agents between two or three separate offices, the contact center decreases the chance that a problem in the building (such as a fire drill) or a technical problem (like a cut fiber optics cable) will take the contact center off-line. If the centers are located near each other, then agents have a back-up location in case a main location is closed. When the centers are located in separate geographic locations, such as different cities or countries, weather, seismic, volcanic, and other nature related issues have less effect on the overall contact center operations.

IP-based contact center and communications solutions streamline the creation of a distributed contact center. The unified desktop provides a method of communication between the centers. An IP-based solution also supplies tools that help supervisors monitor remote agents. Bifurcated or trifurcated contact centers as well as at-home agents provide the best defense against technical and weather issues.

Case studies

Jewelry Retailer

The jewelry retailer is a global on-line and catalog store. It offers customers 24/7, multilingual customer service. Customers are segmented with the most valuable customer (Diamond Level) being served by a select team of highly trained agents. Most callers are routed to the company’s Concierge Service team. The contact center does not use an IVR and all calls are routed directly to agents. The company operates two contact centers, one in Europe and the other in the United States. The U.S. location also supports Canada, Australia, New Zealand, and Asia. The retailer expects call volume to increase starting in the middle of October, peaking in late November and through December, then taper off in the middle of January. A shorter period of increased volume occurs in February and May. During peak seasons, the retailer employs temporary agents to ensure its high service level.

Average Volume:
Non-peak – between 800 and 1000 calls per day
Peak – between 3,000 and 4,000 calls per day

Number of Agents:
25 with increases to approximately 60 in peak times (U.S. only)

Service Level:
80% of calls answered within 10 seconds


  • Maintain high service level and quality of service
  • Provide 24/7 service
  • Reduce operational risks of downtime
  • Support seasonal high-call volumes
  • Support remote, diverse, and distributed agent population
  • Double the workforce with temporary agents during peak season
  • Avoid customers on hold hanging up and calling competitors.

The retailer’s service model is to offer exceptional customer service and it considers the contact centers to be mission-critical operations. Therefore, the contact center cannot experience downtime. The U.S. contact center uses a distributed center model and maintains 12 full-time agents in a second center at the company’s warehouse. This mitigates the risk of the contact center closing due to issues with the building (gas leaks, electrical outage, fire alarm, and so on). Calls enter through the data center located in the headquarters and are distributed, based on the retailer’s defined routing rules, to the appropriate agents, independent of location.

Temporary agents employed during peak season are located in additional seats at the warehouse and in their homes, with the majority of the temporary agents being at -home agents. Agents located at the warehouse connect, as do the other agents, and use the retailer’s internal telephone system. At-home agents connect to the contact center application via a VPN and receive calls either through the agent’s desktop softphone or via an analog telephone in the agent’s home office.

The retailer employs a Mitel UC system, including the Mitel Enterprise Contact Center. Its distributed architecture enables the retailer to reduce operational risks through diversification of the agent’s locations. Mitel’s support for at-home agents allows the retailer to employ agents, regardless of the agents’ location, easily and cost effectively.

The Mitel Communicator unified desktop client provides UC capability that increases the efficiency of the contact center. Agents use the presence status and instant message capability to find and communicate with remote supervisors and expert agents. Trainers and supervisors use the video capability within the desktop to train at-home agents and conduct team meetings more cost effectively.

The distributed capability of Mitel’s IP communication solutions and Mitel Contact Center enables the contact center management to maintain the retailer’s high level of customer service. Supervisors can monitor agent activities, including the at-home agents, as if all agents were still located in a single contact center. This allows supervisors to backup each other, keeping an eye on the agents if one supervisor is in a meeting or out of the office. In addition, supervisors can live-monitor calls and send the agent an instant message with instructions or call feedback. The supervisors can also coach or barge into the call if an agent needs assistance.

Mitel Enterprise Contact Center supplies a full range of reports and dashboards. It offers managers and supervisors real-time and historical reports, thus enabling a 360 degree view of the center’s performance, including agent performance. Mitel’s solutions also provide user defined alerts, which help supervisors react to unexpected events in a timely fashion. Agents are given access to reports and dashboards, which in turn, allows them to view their personal performance and the performance of their team.

The jewelry retailer offers scheduled and Web call backs during peak volume for customers who would prefer not to spend time on hold. The retailer provides its customer with the ability to hold their position in queue virtually, and to call them when their position reaches an agent. The company also offers its customer the opportunity to schedule a call back at a time convenient to the customer through a link on the retailer’s customer service homepage. The virtual queue management and Web call back capabilities of the Mitel Communicator are essential tools that the retail has taken advantage of to maintain their high service levels. Offering customers more control of the interaction increase customer satisfaction.

Dealing with planned and expected increases in call volume requires flexibility. Since management knows the increase is coming, they have time to plan. This retailer effectively maintains its high-service standards by employing flexible contact center architectures. The company also decreases operational risks by distributing the agents, thereby removing a single point of failure. Finally, the retailer enables the customer to control when he or she would like to be contacted by providing scheduled call back in periods of high-wait times. While high volumes can drive customers to competitors if not handled effectively, this retailer has taken advantage of the flexibility and distributed nature of the Mitel solutions to maintain a high level of customer service.

Medical Information Center

The medical information center answers medical related questions, such as questions about poisons and food borne pathogens. The center operates a virtual 24/7 contact center staffed by medical professionals (nurses, doctors, and physician’s assistants). Volume is stable but the center experiences increases (upwards to 10 times normal volume) during medical emergencies, such as an outbreak of e-coli or salmonella contaminations. Spikes occur with little warning. Because many of the calls are concerning life threatening issues, calls cannot be placed on hold.

Average Volume:
Between 500 – 600 calls a day
Peak – during crisis, volume can increase by 6 or 10 times

Number of Agents:
30 plus medical professionals

Service Level:
80% of calls answered within 30 seconds


  • They can search out a competitor, or
  • They can call the company with high volume again.
    • Maintain high service level and quality of service
    • Provide 24/7 service
    • Reduce operational risks of downtime
    • Support seasonal high-call volumes
    • Support remote, diverse, and distributed agent population
    • Double the workforce with temporary agents during peak season
    • Avoid customers on hold hanging up and calling competitors.

The medical information contact center deals with life threatening events and must keep hold times very low or nonexistent. Normally that is not a problem. However, when emergencies develop, such as when peanut butter was contaminated with salmonella in June 2009, volumes can increase up to 10 times the norm. Nevertheless, hold times must still be held to very low levels; ideally, there should be no hold times at all.

The center is staffed by medical professionals, mostly nurses. To make the center more appealing and to expand the geographical range of potential agents, the medical information center uses a virtual contact center model and some nurse’s work from remote offices. These nurses connect to the contact center through a Citrix Server XenApp or by calling into an IVR to establish and open a telephone circuit. Expert agents, mostly doctors, connect to the contact center through a mobile interface. Nurses and doctors use instant messages and text messages to collaborate when necessary.

Since the center cannot add temporary agents, it must rely on call avoidance to maintain a reasonable wait time. It provides instructions and keeps the public informed through IVR messages. Messages are updated frequently and on the fly to supply as much information to the public as possible. The center also employs social media, such as Facebook and Twitter, to provide outbound notifications and up-to-date information to the public.

The medical information department relies heavily on the flexibility and features offered by Mitel Enterprise Contact Center along with the Mitel Communicator unified desktop. By using virtual technologies, the contact center avoids the expense and labor of installing applications on agent computers, or issuing and tracking laptops for doctors or remote nurses. This greatly streamlines the onboarding processes and helps control contact center costs. The center also relies on the desktop Web chat capability to allow residents to chat with nurses.

The unified communication capability of the desktop enhances collaboration between agents and experts. The instant message and chat features allow nurses to speak to each other and the desktop’s presence status feature allows nurses to find doctors when they need additional information.

Mitel’s reporting capability allows the center to create density analyses of outbreaks. The center sends the reports to the appropriate local, state and federal governments who then use the density information to allocate resources and alert first-responders of the potential impact of the outbreaks.

The medical information line has a finite number of agents and when an outbreak occurs, the center needs to react quickly. Nurses can log in quickly to the Mitel system, and the center can provide up-to-the date information to the concerned public, discouraging continual calling for information. Finally, the solution provides important information to government agencies, enabling them to react more effectively.

Public Utility

The public utility contact center answers questions regarding billing, usage, and emergencies. The center is open 8:00 a.m. to 6:00 p.m. Monday through Friday. All agents are in a single center. Management tracks calls by zip code in cases of utility outage. Residents with special needs (immobility, dialysis machines, breathing machines, etc.) have priority in the queue if their numbers are registered. All other calls have lower and equal priority.

Average Volume:
Non-peak – 2,000 calls per day
Peak – during a crisis, volume can increase by 6 or 10 times normal, very quickly for short periods.

Number of Agents:

Service Level:
80% of calls answered in 60 seconds


  • 24/7 coverage
  • All agents are virtual
  • Calls cannot be kept on hold
  • Can experience huge spikes in volumes with little or no warning
  • Customers on hold will hang up and call back

Call volumes at this public utility are stable, until something happens, like a water main break and then the volume spikes very quickly. There is no warning and the first time the supervisors find out about the emergency is through queue activity. Since hold times increase precipitously, customers will hang up and call back rather than stay on hold.

The contact center employs a large wallboard to list the queues and number of calls based on zip code. This gives supervisors a visual escalation path, indicating the severity of the issue. The wallboard uses the open real-time event feed information streaming from Mitel Enterprise Contact Center to mesh it with their own call analytics data providing a consolidated view for supervisors.

Management uses call avoidance to decrease call volume. The supervisors will quickly move a pre-recorded message onto the IVR, indicating there are issues in specific zip codes. The message will also inform the caller of the estimated repair time. As more information is gathered, supervisors update messages with additional zip codes and new repair times.

During utility outages, the contact center creates and launches an outbound broadcast campaign using the integrated outbound functionality built into the Mitel Enterprise Contact Center. The campaign calls the residents of the affected area, informs them of the issue, offers safety information, and provides an estimated time to repair.

Like most local government organizations, costs are a concern. This public utility employs SIP trunks to reduce the telephone costs.

The public utility makes full use of the on-the-fly capability of Mitel’s IVR. Supervisors can make changes to the IVR messages as the situation changes and keep the public informed with up-to-date information. Mitel Contact Center dialing capability lets the contact center create and execute an agentless broadcast campaign. This effective use of an outbound campaign provides useful information to the affected population and can increase customer satisfaction and loyalty without taking agents away from inbound calls. If customers are kept informed, they are better positioned to make decisions and thereby avoid calling the contact center.


All contact centers must manage high volumes at one time or another. If not managed properly, expected and unexpected spikes can greatly affect a company’s bottom line, customer satisfaction, and employee satisfaction. Managing the internal risk factors is the first level of defense that will lead to other, more creative solutions. Today’s IP-based contact center and communications solutions provide contact centers with flexibility and functionality to create workable solutions for one of the major problems faced by call centers today – one that will not be going away any time soon.

Mitel. Brilliantly simple business communications.

Mitel, Inc. (NASDAQ: SHOR) is a leading provider of brilliantly simple IP phone systems and unified communications solutions powering today’s always-on workforce. Its flexible communications solutions for on-premises, cloud and hybrid environments eliminate complexity, reduce costs and improve productivity.


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