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Soft PBX adds flexibility to VoIP business continuity strategy

Legacy TDM voice was often too expensive to build into a business continuity strategy. VoIP changed that, and some UC managers find more flexibility in soft PBX platforms.

One of the communications services that enterprises depend upon most in an emergency—voice—has traditionally been the hardest to build into a unified communications (UC) business continuity strategy because legacy PBXs and trunks are so bound to fixed locations. Voice over IP (VoIP) changed that. Backup data connections are now potential phone lines, and some UC managers are finding that software-based PBXs, or soft PBXs, afford them even more flexibility than dedicated IP PBX appliances.    

The primary data center for 1st Guard Truck Insurance, an insurance company for truckers, is in Venice, Fla., directly in the path of the devastating hurricanes which hammer the Gulf Coast each year. CIO Dan Ribar had built a cost-effective business continuity strategy around every IT service and application except voice—an unacceptable omission for a small business that does nearly all of its sales via the phone and Internet.

"If 1st Guard loses its offices for any reason—be it hurricane, fire or wild pigs—it's great that we've got our data someplace else, and it's great that we've set up our business systems for Web access, but what do you do with the phones? How do you move phones easily?" Ribar said. "Our old business continuance and disaster recovery plan included a contracted office space—only because of our phone system."

It's a common gripe among telecom engineers still using legacy TDM PBXs, said Zeus Kerravala, senior vice president and distinguished research fellow at Yankee Group.

Our old business continuance and disaster recovery plan included a contracted office space—only because of our phone system.

Dan Ribar
CIO, 1st Guard Truck Insurance

"Historically, if you lost your PBX, you lost your voice services," Kerravala said. "You could set up a redundant PBX if you wanted to, but that was pretty expensive."

But "the weakest link" in Ribar's business continuity strategy wasn't a legacy TDM PBX. It was an Avaya IP PBX appliance deployed in his data center five years ago—hardly a fossil—to support softphones. It didn't support SIP trunking for external calls, which would have made buying a second one an expensive choice for a hot spare in a colocation facility or hosted environment.

"We did not want to have 24 channels live all the time at the hot site with a PRI," Ribar said.

Upgrading to a newer model and putting it in a hosted environment was also out of his budget. Additionally, the legacy IP PBX had only supported Avaya's proprietary softphone client and was Windows-centric. That may have sufficed on a typical business day, but not when a hurricane shut down the office, Ribar said.

"We needed to be able to 'transition' during an emergency, which meant I wouldn't have my PC laptop with me but [would need to] run [our softphone client] on my iPhone, Android [device], PC or Mac," he said.

Varying vendor support for soft PBX and call control

An IP PBX essentially operates call control as an application on a server and had traditionally operated as dedicated appliances. Most large UC vendors have integrated other applications into the same hardware and positioned these products more as UC platforms that have virtualized the IP PBX software alongside other services, such as IM and presence.

Some UC vendors—including Microsoft, Cisco Systems and Avaya—limit support for their soft PBX to a proprietary appliance, hypervisor, host operating system and/or virtualization architecture. 

Microsoft Lync can be deployed in a virtualized environment, but it requires the Windows Server 2008 R2 operating system. Support is only certified for Microsoft's Hyper-V hypervisor and VMware ESX 4.0. Microsoft, however, maintains that its intrinsic software approach meets customers' needs for business continuity.

"Resilient systems aren't worth much if you have to be in the office to use them but can't get there," said B.J. Haberkorn, a group product manager for Lync at Microsoft. "The servers that make up a Lync 'system' can sit in two separate data centers, and if one data center goes offline, communications can continue uninterrupted ... anywhere with an Internet connection." 

In contrast, other soft PBXs can run on industry standard servers, various operating systems and potentially, depending on the software and hardware capabilities, as an instance in a multi-tenant virtualized environment. Increased adoption of cloud-based soft PBXs is not far off, Kerravala said.

"The software instance gives you a lot more flexibility because you can choose your hardware platform and use some virtualization tools to create more efficiency," he said. "You [shouldn't] have just one instance of an IP PBX. Have three or four of them behind a load balancer."

Setting up a hot site with a soft PBX often requires additional licensing and configurations, according to Dave Michels, an independent telephony consultant based in Boulder, Colo. Telecom managers should ensure that their wide area network (WAN) connection to the backup site has the appropriate levels of bandwidth, latency and loss, he said.

UC vendor Mitel, which divorced its IP PBX software from its hardware upon releasing its Freedom Architecture portfolio released last year, has seen growing interest from customers for soft PBXs in cloud computing environments, according to Stephen Brown, vice president of systems engineering at Mitel.

Experimenting with a soft PBX as part of business continuity strategy is a common first step for enterprises interested in cloud-based UC, Brown said.

"In three or five years, all call control is going to be virtualized," he said. "Customers are not going to continue to invest in legacy or traditional ways of deploying a solution."

Soft PBX for business continuity: More than forwarding calls

Ribar replaced his legacy IP PBX with one based on Asterisk, an open source IP PBX project designed to run on standard servers and assorted operating systems. On its own, Linux-based Asterisk functions as a true soft PBX. But for UC pros who lack the programming skills to build their own soft PBX server or are looking for commercial support, there are low-cost turnkey appliances from vendors such as Digium and Fonality that maintain the open environment of Asterisk.

Ribar deployed Switchvox, a turnkey appliance that runs Asterisk. The appliance is sold by Digium, a company founded by Asterisk creator Mark Spencer. Using Asterisk's software development kit (SDK), his team built other UC and contact center tools into it, including an application that automatically calls customers with overdue balances and connects them to an interactive voice response (IVR) system.

A backup Switchvox server is always online at 1st Guard's colocation space in Dallas, Ribar said. In the event of a disaster, he uses an automated system from his service provider to redirect inbound calls on the company's 15 toll-free numbers to the Dallas appliance, which reroutes the calls and enables users to maintain direct inward dialing (DID) and call queuing from any device running the softphone client. The backup also maintains custom applications, such as the auto-dialer.

Before deploying Switchvox in December, a disaster required users to be their own call control managers. Users would have to manually find colleagues' cell phone numbers and remember how to transfer calls with their device's native capabilities, Ribar said. 

"It was important to us that in this disaster mode when we've actually switched over [to the hot site] to be able to use [our other devices as if] we still had a PBX in the middle," he said. "In our environment now, if you are extension 101 and I'm 100, I take the phone call on my Bria [softphone] client—not the iPhone, but my Bria client—and transfer it to extension 101 via my PBX."

Let us know what you think about the story; email: Jessica Scarpati, News Writer.

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