Network automatic call distribution, or NACD, is a sophisticated electronic switching system that routes call traffic across a network. This capability allows agencies to standardize or share call center operations across diverse physical locations as part of a single enterprise or to enhance regional coordination of individual sites. It also enables public-safety answering points to network multiple call-distribution systems and combine their resources to work collectively as one redundant virtual call center.

NACD utilizes private or public network facilities to queue, route and reroute calls across sites to available agents or specific designated recipients. Routing is transparent to the caller regardless of distance or location; meanwhile, PSAPs can expand their coverage areas and balance calls among sites during day-to-day operations and crisis situations. In short, NACD enables redundant ACD operations across geographically separated sites.

Next-generation 911 objectives include improving PSAP backup, overflow, business continuity, and disaster recovery capabilities. NACD provides resiliency and redundancy to network-based extended call center operations, ensuring service continuity and speeding recovery from service interruptions. Its load-balancing capabilities can spread the call volume among agents at multiple locations, and it can automatically route calls to agents with specialized skill sets located anyplace on the network.

Call-center resources can be leveraged over the network geographically for staff sharing or leveling. Resources can be managed by service discipline (police, fire or EMS), by emergency or non-emergency designation (911 vs. 311), or by special skills (e.g., SWAT, bomb squad, hazmat, or language proficiency).

Sometimes referred to as “best selective routing,” NACD enables master call distribution among multiple linked ACD queues, with each maintaining its own routing autonomy. Individual sites participating in such a deployment would be assured of local control over their business rules for prioritizing and answering calls, and would be unaffected by the decisions of other sites because NACD allows each site to implement its own local ACD routing policy. For instance, the following routing policies all could co-exist simultaneously within a multiple-site ACD deployment:

  • Site A: Circular routing. Presents the call to the next available call-taker in round-robin fashion within the group.
  • Site B: Linear routing. Presents the call to the first available call-taker within the group with the highest priority setting.
  • Site C: Longest idle. As the name suggests, this policy results in the call going to the call-taker in the group who has been idled for the longest period of time.
  • Site D: Ring all. Directs the call to all available call takers in the group simultaneously.

NACD can be combined with local survivable sites using remote media gateways and other technologies to create robust and resilient virtual call-distribution capabilities that continue to operate in the face of practically any disaster scenario.

For example, given suitable infrastructure, calls ordinarily are distributed across Site A and Site B using NACD. If one side of the WAN were to become unavailable, or if Site A is physically disrupted, Site B will continue operations normally without interruption by handling all calls — including calls formerly intended for Site A. This transition to survivable localized operations will be transparent to callers and seamless to call-takers.

Traditional queue-based ACD simply concerns itself with routing calls; in contrast, advanced skills-based ACD focuses on who the calls are routed to. Combining skills-based routing with NACD allows call center resources to be reached quickly and efficiently, regardless of where they reside on the network.
For instance, interactive response (i.e., push “1” for fire, “2” for police, or “3” for ambulance) or interactive voice response — the use of voice commands instead of touch-tone responses — can help prioritize emergency calls while directing non-emergencies to lower queues. Once the nature of each call has been ascertained, it quickly and efficiently can be directed to the most appropriate call-taker, regardless of his physical location.

NACD adds robustness and geographic reach to any entity contemplating the sharing of calls among multiple sites. Its powerful capabilities in furtherance of NG-911 objectives will serve PSAP managers well, whether they coordinate centralized call distribution or manage a local site with unique routing considerations.

Michael Rosen is a technical product manager for PlantCML. He can be reached at

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