
We explain what an ACD (automatic call distributor) is and how contact centres use ACD systems.
ACD stands for Automatic Call Distributor.
An Automatic Call Distributor (ACD) answers incoming calls and routes them to the right contact centre advisors.
ACDs have two main functions. If no calls are waiting, the ACD routes the call to the advisor who has waited the longest.
Secondly, if there is a queue, the longest-waiting caller will be routed through to the next available advisor.

However, as ACD systems got smarter over time they were able to route customers in more sophisticated ways.
For example, ACDs can allow for a priority queue, with its algorithm distinguishing between high- and lower-value customers.
This places different customer groups in separate queues, helping high-value customers avoid long hold times.
However, these systems are quite an evolution from those that first entered the contact centre in the 1970s…
Before ACD systems, the earliest contact centres had two methods of distributing calls to advisors.
Switchboard operators first identified each call type and connected callers to the advisor best suited to help.

Next came hunt groups, which sent calls to a specific advisor first. If they were unavailable, the system tried the next advisor. So there was a designated chain of advisors that all calls would be passed through.
Both options remained popular until early ACDs arrived. These systems matched waiting calls with advisors who had been idle the longest.
If no calls were queuing, the system could also evenly distribute calls amongst advisors, so everyone had the same workload.
Initially, hunt groups were as popular as ACD systems. They came with telephone switchboards, while ACDs cost extra.
In the late 1980s, ACD technology became an add-on to PABX (Private Automated Business Exchanges) systems, which were implemented in all large-scale call centres.
By the late 1980s, ACD technology became an add-on to PABX (Private Automated Branch Exchange) systems. Large call centres widely adopted these systems.
Since then, ACD systems have become a fundamental piece of technology. ACD algorithms have become more complex, allowing contact centres to route customers to the most suitable advisors.
Modern contact centres use complex routing rules. These consider advisor availability and skills when matching customers with the right person.
For example, by using a modern ACD system to route customers, you can apply the following rules:
Then we have to consider that contact centres cater for more than just voice calls. So modern ACD systems have to work conveniently with other channels that your customers use to contact you. These may include email, live chat, messaging apps, social media and video.

As Michael McKinlay, CEO at Sytel, says: “Traditional ACD manufacturers needed to react to these changes by building systems that can truly handle multiple media types and multiple sessions for each advisor, with full media blending (and not just call blending) across all media types.”
“Systems that are siloed and do not fully blend both voice AND digital sessions may have a limited shelf life in this brave new world.”
Some contact centres use ACD systems with a single queue for all contact types. This is known as multichannel queuing. This works by pushing contacts to the next available advisor based on their skills profile.
Modern ACDs route contacts across all channels based on advisor skills. They can also:
ACD data helps contact centres track metrics, forecast demand, schedule advisors and identify calls for quality analysis. This data includes handling times, calls-per-day and transfers.
If your organisation operates across multiple sites, an ACD can unite them into one contact centre and simplify transfers. It can also allow for homeworking, although being in the cloud is equally important for this.
As the ACD system can identify who is calling, the contact centre can not only prioritise calls but block certain numbers. This is useful for those callers who persist in making nuisance calls, physical threats etc.
Integrating your ACD with other contact centre technologies can unlock further benefits.
To find out more innovative ways of routing customers through an ACD system, read our article: 10 Call Routing Strategies That Actually Work
To maximise the potential of your ACD system, here are a couple of integrations that you should consider.
Your CRM system will contain individual profiles for each of your customers with information such as their gender, age, address, etc. It will also contain notes of an advisor’s after-call work (ACW) – i.e. call summaries – from all of the customer’s previous interactions.
However, it will likely not include other useful information such as contact type, handle times and holds/transfers, which is all held in the ACD system.
Without CRM and ACD integration, advisors must either work without useful information or switch between both systems during calls.
You can also install screen pop technology alongside your integrated ACD and CRM, which presents the customer’s information on the advisor’s desktop as soon as the customer calls in.
Integrating both systems lets the CRM store ACD data in customer profiles, giving advisors all the information they need in one place.
But if you want to go one step further, you can also install screen pop technology alongside your integrated ACD and CRM, which presents the customer’s information on the advisor’s desktop as soon as the customer calls in.
By integrating your ACD and IVR, you can create navigation messages to play to your callers.
When a call enters the contact centre, it is first passed through the ACD system to check the rules for what happens to calls from that number – i.e. should they be passed to a specialist advisor?
When a call enters the contact centre, it is first passed through the ACD system to check the rules for what happens to calls from that number.

Then, if integrated, the call is fed into the IVR, which asks the customer to “press…” to identify what their reason for calling is. With this information, the call is directed by the ACD to the most appropriate advisor.
So, as Daniel May, a Sales Executive at Business Systems, says: “By integrating your ACD with the IVR you are routing customers based on both the rules within your ACD system and the customer’s selection.”
Throughout this article, we have highlighted a great number of benefits that a modern ACD can give us, but here are two more that have not yet been mentioned.
By integrating a modern ACD with your IVR system, you can better manage call queues by providing customers with estimated wait times and callbacks.
The ACD will provide the data of how long the wait time is. This is then transferred to the IVR, which communicates the wait time to the customer, who then has the option of pressing a number to receive a callback.
The callback works so that the caller’s place in the queue is saved by the ACD system and then, once the customer reaches the front of the queue, they get a callback. This prevents the customer from having to stay on the phone and listen to “that” hold music.
Modern ACDs can function across multiple sites, which is great for business continuity.
For example, if your contact centre is hit by a disaster, such as vandalism, snow or public transport disruption, advisors can work from home or you can move to another site without needing a separate ACD system.
However, to attain this benefit, you must ensure that your ACD is a scalable, secure and reliable system that is capable of supporting such critical operations.
Arguably the greatest benefit of an ACD is the technology’s ability to route customers based on advisor skills. However, a new technology is beginning to come to the fore that routes customers differently.
Predictive routing is a technology that uses Artificial Intelligence (AI) to analyse all of a customer’s data against an advisor’s performance data and attributes.
Predictive routing is a technology that uses Artificial Intelligence (AI) to analyse all of a customer’s data against an advisor’s performance data and attributes.
It then comes up with a forecast Net Promoter Score (NPS) for each interaction the customer could possibly have with every advisor in the contact centre. Based on these scores, the technology routes the customer through to the advisor they are projected to have the best rapport with.
However, while this might be the future of call routing, for the foreseeable future the ACD systems will remain a fundamental piece of technology for the contact centre, due to the data it stores and all of the other benefits above.
For information about purchasing an ACD system, take a look at the following article: What to Look for When Buying an ACD System
An ACD system is a technology that distributes contacts to various advisors within the contact centre based on the rules that are written into its algorithm.
While the first ACDs could only pass a call on to the next available advisor, the technology has developed to cover a number of different channels and can route contacts based on a number of different factors.
These factors typically include customer data, advisor skills and advisor availability; however, purpose of calling could also be a factor if the ACD is integrated with the IVR.
Another integration that helps to maximise the potential of an ACD is to integrate with your CRM system and screen pop. This is because the ACD is not all about routing, it also contains valuable data, which – when integrated with these technologies – can better inform advisors during calls.
However, some believe that while there are many benefits to installing an ACD system, predictive routing may one day take over, using AI in an innovative way.
For now at least, though, the ACD remains a technology that is right at the heart of the contact centre.