Efficiency Indicators – Call Volumes/Abandoned Rate/Blockage

In the last two issues, we discussed certain operational indicators such as AHT, Service Level, ASA and Occupancy Rate. In this issue we tackle a few more operational indicators such as Call Volume, Abandoned Rate and Blockage. Although these indicators may not reflect the efficiencies associated with the daily operation of the centre, they are a significant part of the long-term planning for the centre.

Call Volume

As the name indicates, this is the number of calls or contacts received by the centre (technically, the volume is measured at the point of entry into the queue – calls handled within the IVR are measured separately). In practice there are two sets of numbers: Offered and Accepted. Both are reported by your ACD or switch. Offered Calls refers to the total number of calls arriving at the queue. Accepted Calls are the number of the calls handled by the agents. Call Volumes can be represented on a Yearly, Monthly, Weekly and Daily basis. For the purpose of Work Force Management (WFM), Call Volumes are often broken down into 15 minutes intervals. Call Volume represents the work-load that a centre must handle and although the calls are initiated by individual customers (in a rather random fashion), a good forecasting process can predict the volume demand with a very high degree of accuracy. Actual Call Volumes are tracked and provide information for any Intra-Day adjustment as well as short and long-term forecasting.

Abandoned Rate

Abandoned Rate represents the percentage of calls (Offered) that are terminated while in the queue waiting to be answered (in plain English, the customers hang up). Although technically all the calls that were not answered by an agent (difference between Offered and Accepted) can be considered Abandoned. Many centres only count the calls that were abandoned (terminated) after the Service Level threshold. This methodology assumes that there were other circumstances (outside the control of the centre) contributing to the caller deciding to terminate the call. Regardless the centre was not anticipating being able to answer the call, due to the Service Level threshold. Using this “over the threshold” approach an Abandoned Rate of around 1% is acceptable in most centres. Where 100% of all abandoned calls are considered the percentage becomes higher, to around 3%. Obviously a higher rate indicates a busier centre, longer wait time and more frustrated callers.


Blockage refers to the percentage of calls that are initiated by the customers but do not reach the centre due to lack of available circuits, lines or trunks (customers hear a fast busy signal). The lack of circuits can be between the caller and their central office, on the telephone service provider network or lastly and most commonly into the centre.

This is a measure of accessibility which unfortunately is ignored (not reported) in many centres. One reason for the lack of attention could be that in order to assess and report on blockage, a report cannot be generated by the centre and must be requested from the telecom service provider. This can be a difficult and time-consuming process. But make no mistake there is a great risk in not knowing!!! The centre may be conducting a reasonably efficient operation and providing services for the number of calls that make it through but what about the unknown number of callers who never get to the centre?

Are there tens, hundreds or thousands of customers that are basically denied a contact with the centre? What is this doing to your customer satisfaction? And what if the lines were to be expanded in order to allow the entire workload to arrive at the queue? Is the centre capable of handling this extra load? What would accepting all calls do to recruiting, staffing, WFM processes, not to mention budgets? It is important to mention here that blockage can be manipulated by the unscrupulous. By reducing lines and therefore access fewer calls will be received and more calls will be handled with the Service Level threshold. By ‘choking’ the incoming volume and not servicing customers the centre can still achieve the Service Level objectives but at the cost of increased customer dissatisfaction.

Improving Operational Results

Now that we understand the meaning of these indicators, what can we do to improve the results? In case of the Blockage, the answer is easy: a periodic traffic study by the telecom provider can not only provide the Blockage Rate (including the time of the day/week), but also the required number of lines (trunk) that would be required to handle such traffic. Call centre management, however, must be diligent in aligning the internal capacity of the centre (staffs, stations, networks) with the external capacity before adding more trunks thus opening the door to the extra work load as there is very little to gain by simply opening the door only for customers to experience long wait times in the queue.

As for improving the Abandoned Rate, the answer lies within a proficient Work Force Management process including appropriate planning and allocation of resources. In achieving the target Service Level, call centres minimize the wait time for the customers and thus removing the frustration and the need/urge to hang up. In addition available technologies such as “Call Back” feature (as part of the queue) can allow the customers to avoid long wait time and potentially “hang up” by effectively scheduling their calls for a more convenient time frame.

Improving Call Volumes?

In most centres it is simply accepted as a fact that calls are driven by number of factors that are entirely outside the control of the centre. In many cases the management has improved the WFM process significantly to ensure they can predict the number of calls with accuracy and confidence. In addition they may have established a close relationship with the other departments within the organization to gather first hand (and prior) knowledge to any activities that might increase the call volume such as introduction of new products or a marketing blitz.

More recently, by the introduction of the Internet, more and more organizations try to direct customers towards their web sites. Costs are the main reason as it is significantly less expensive to provide certain services through the web – and other automated methods like IVR– than providing them with a live voice. This diversion is most commonly done through an audio message played to callers in queue suggesting they can likely get help faster by going to the company website. But what about the remainder of calls that must be handled at the centre or in case of smaller organizations who do not have the high volume in order to justify web development expenses?

This is when the management can investigate the Preventable Calls. These are the type of the calls that could be prevented proactively by either reaching out to the customer via other channels (including emails, voicemail and an outbound call) or ensuring a complete (quality) call in the first place as discussed in the previous issues. For example, updates to a lengthy process (such as a complaint) can be provided to the customer on regular and pre-set intervals thus removing the need for the customer to call the centre.

The Bottom Line

Although not perceived as a top Operational Indicator, Call Volume is a critical part of managing a contact centre as it directly relates to the overall work-load and associated expenses. While Abandoned and Blockage Rates are by-products of other internal and external factors, they have a significant impact on the overall customer satisfaction and must be tracked, managed and if necessary improved.

This article was originally published in The Taylor Reach Group newsletter.