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Industry Insight
January 2002

Jim Machi

VPN: The Enterprise VoIP Darling


In last month�s column we explored the renewed interest in enterprise VoIP. We also discussed how �enterprise convergence� can mean different things to different people. For instance, convergence could mean anything from a full-scale IP-PBX environment with IP phones, to using IP via the company intranet as �trunks� to connect disparate PBXs. This month we�ll look at how and why virtual private networks (VPNs) might be the right vehicle to bring the economics of VoIP to any size company.

A Solid Choice For The Enterprise?
Let�s start by considering why VPNs are a good choice for many enterprises. If you look around your office and compare the work environment to, say, two or three years ago, you will surely note that more employees are now working from home. While many things contributed to this trend (like who wants to actually see your boss every day), one of the biggest factors supporting this shift is surely the emergence of cable modem and DSL technology to the home, making data rates more �workable.� Also, corporate enterprises are moving away from dial-in modem banks to using ISPs that support DSL and cable modem last-mile technology. This allows the corporations to support VPNs to the ISPs. In short, the infrastructure is there to support VoIP using VPNs.

It�s easy to see the possibility of putting voice over these VPN networks � after all, the infrastructure would exist to do it. And if an enterprise supplied its remote workers or a small branch office with VoIP software clients, the capability would also be there for integration to the corporate PBX provided the premise PBX was IP enabled, that is if either a gateway existed between the LAN and PBX or if the PBX were LAN-enabled, or a LAN PBX, to begin with. In fact, the July 2001 IDC report, �Calling the Enterprise: IP Telephony Services to the Business Market,� predicts a whopping 527 percent compound annual growth rate (CAGR) of corporate IP telephony minutes to 127 billion by 2005.

This nirvana would allow remote workers to access the corporate PBX for long-distance calls, voice mail, and conference calling, while also allowing incoming calls to be automatically routed to the remote worker�s laptop via a screen pop. If we�re talking about a small branch office, there would be no need for a PBX or key system in that office. Perfect, right? Not quite. After all, if it were perfect, everyone would have already done it.

One drawback is that not all businesses use VPNs. Small businesses, my research shows, currently only have VPNs in place if they�re engaging in some type of e-commerce activity � potentially with a vendor or customer. But while this is the case today, e-commerce activity in this environment can only increase � which means the use of VPNs in this environment will increase. VoIP, using VPN technology, will be a huge contributing factor to the growth expected in this marketplace.

There are other reasons companies don�t use VoIP over a VPN network today. Full-scale VPNs don�t make sense for every company due to security concerns and the difficulty of convergence integration. Also, today VPN offers secure services using encryption schemes. While encryption can be used with VoIP, encryption and decryption would add latency and degrade QoS � probably to the point where business customers would find it unacceptable. To use VoIP over VPN, encryption would mostly likely need to be turned off for calls that end up outside the VPN � again, probably unacceptable to most businesses. Access to the corporate LAN by way of unauthorized VoIP access is simply too big a risk for most businesses to take. 

In terms of integration, service providers aren�t yet offering customer premise equipment (CPE)-based VPN services that seamlessly integrate VoIP. For example, considering the security concerns we just cited, what company would allow an out-of-premise VPN call? Think about your typical daily call load. How many calls are between members of your own company, and how many are to outside the company? 

I would guess that at least half of your daily calls are to parties outside your own company. If you were an IT manager, would you want to subject your network to that kind of risk?

That�s not to say VoIP in the enterprise won�t achieve IDC�s growth predictions. While some calls � most likely intra-company calls � will be using VPN, others will not. An enterprise will still be able to use VoIP without a VPN if the company has an arrangement with a next-gen telco to provide these services whenever an employee dials an out-of-company extension.

Panacea Or ???
So let�s revisit the original question in last month�s column: Is VPN a VoIP enterprise panacea? Not completely, since enterprise VoIP means much more than putting voice over a VPN. But even so, a VPN can certainly be an extremely important vehicle to increase the use of, and dependence on, VoIP in the enterprise. And I think we�ll see many more applications take advantage of VoIP in 2002.

Jim Machi is director, product management, CT Server and IPT Products, for Dialogic Corporation (an Intel company). Dialogic is a leading manufacturer of high-performance, standards-based computer telephony components. Dialogic products are used in fax, data, voice recognition, speech synthesis, and call center management CT applications. For more information, visit the Dialogic Web site at www.dialogic.com.

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