IP contact centers can benefit from virtualization as much as any other technology, but because of the real-time nature and need for reliability, deploying virtual machines in this environment requires care in selection of hardware, segmentation of applications and the use of replicating virtual machines on the fly.
Contact-center elements such as voice, interactive voice response (IVR), automated call distribution (ACD) and conference bridging require near-real-time response, so virtual machines supporting them need enough dedicated horsepower, says Patrick Conroy, CTO of contact-center software vendor Callfinity, which also installs its products.
Designing the contact center requires dedicating CPU and memory to the real-time applications that need them, Conroy says. Virtual machines not running real-time applications can share remaining resources without dire consequences.
Contact centers also include less-time-sensitive business applications that pop up on call agents' PC screens to handle callers' needs and that can handle greater delay.
"So your file server or your Exchange server or whatever the case may be may wind up running low on CPU or RAM, but it's not as critical as your phone system or your ACD or your IVR," he says.
Separation of contact-center elements on different servers also is important, Conroy says. For instance, databases tapped by multiple applications should be put on separate servers where they are unaffected by CPU and memory demands of other applications to ensure their availability.
In a typical deployment, Conroy will place a single, critical contact-center application such as telephony on a physical host with other applications that are less critical, "so if you need more capacity for your telephony layer, you take away resources from your less important virtual servers."
Others take a more cautious approach. For instance, contact-center vendor Aspect Software deploys only its own applications on virtual servers within a given physical host, says Roger Sumner, senior vice president of technology and architecture for the firm. No third-party business applications are allowed, he says.
"Over time I think the technology will be there within virtual machines to allow mixing applications," he says, "but we'll be very guarded in that area because we want to ensure that applications get delivered in an appropriate amount of time."
Meanwhile, Aspect is gathering data about the effects that other applications on the same physical host have on the real-time data center applications. Virtual environments allow setting of parameters that help ensure contact-center applications get the performance required from CPU, memory and bandwidth, says Sumner. "But when you exceed those parameters the behavior of our applications isn't as predictable," he says.