September 1998

BY TONY MORRIS

Merging voice with data over a single network is becoming an increasingly widespread practice for one very good reason: It saves money. By consolidating traffic, annual voice communications costs can be dramatically lowered, sometimes by as much as 90 percent. Equally important, while the gateway technology required to reap these savings certainly has an attached cost, payback is swift. Depending on call volumes and network configurations, a complete ROI may be achieved in less than six months. From there on out, savings continue long into the future and go right to the bottom line.

DATA OVER VOICE LINES
The concept of leveraging communications networks by consolidating voice and data traffic is not new. In the 1980s, companies began carrying data traffic on the excess bandwidth associated with the TDM (time division multiplexed) voice networks they had implemented as a lower-cost alternative to the public switched telephone network (PSTN).

With the emergence of client/server networking and the surging use of the Internet, this voice-based communications paradigm began to change as data traffic started to consume a far greater percentage of network bandwidth. The result: Frame relay circuits proliferated for data communications because they were as much as 50 percent less expensive than leased lines. However, because this technology was not well-designed for voice communications, dedicated T1s remained the channel of choice for telephony.

VOICE OVER DATA CHANNELS
As voice compression technologies advanced in the mid-1990s, data and voice again began to merge, this time on frame relay networks. This innovation precipitated the great communications flip-flop: Where once excess capacity on voice networks was used to carry data traffic, now voice traffic was becoming the freeloader.

The ubiquity of routed IP networks, and the desire to trim telephony costs, is now driving this trend - and the market for voice gateways. As stated above, the reason for the popularity of these gateways is simple to understand: They provide a way to leverage existing network resources and to dramatically reduce, or even eliminate, telephony costs.

Take the scenario, for example, of a company that already has an IP network in place at locations in London and New York City. By placing a voice gateway between the network routers and the PBXs at each of these sites, voice traffic can piggyback the frame relay WAN link between these cities. As a result, otherwise expensive international calls can now be achieved for free. Alternatively, if no WAN link existed, but each site had a local point of presence (POP) for router-based Internet connectivity, the voice call could go out over the Internet -- again at no additional cost beyond the monthly service charge for the POP.

With benefits so significant, the question companies should be asking themselves is not when to add voice capabilities to their data networks, but rather how to do so in such a way that voice quality is optimized, costs are minimized, and ongoing benefits maximized. The answer: Find a technology that supports telephony -- including both voice and fax -- over a variety of infrastructures including frame relay, IP, and the Internet.

VOICE AND FAX
Both voice and fax should be supported because, no matter how much companies strive to become paperless, fax has become an accepted business medium -- and is likely to continue to be so, despite the proliferation of e-mail. Therefore, it would be an oversight to ignore connect charges associated with faxing when implementing technology to reduce overall telephony costs. To ensure maximum utility, the gateway should be able to identify a call as voice or fax -- on-the-fly -- to eliminate the need for separate ports for each medium.

MULTIPROTOCOL SUPPORT
Frame relay, IP, and the Internet should all be supported by the gateway solution because in an enterprise, any, or all, of these communications links may exist between any two sites. With the flexibility to carry voice over all of these links, investments can be protected, even while all resources are leveraged. This approach also empowers companies to selectively allocate differing communications networks for various needs, selecting the one for each application that makes the most sense on a cost and quality basis.

For example, for voice calls between sites A and B that have both frame relay and IP network links, the frame relay channel could be selected for voice because with compression 12 voice channels can be carried in a 64 Kbps circuit (only 10 can be carried on this same circuit with IP). However, between sites B and C that have IP and Internet channels available, the IP would be favored for voice because quality tends to be higher. However, to optimize bandwidth of the IP link, faxes could be sent over the Internet since they maintain their integrity better in this media than voice calls. To ensure optimal communications between all sites, the gateway should also feature any-to-any linking so that a voice call can come into one site via IP, be switched out over Frame Relay, and reach a final destination via the Internet.

To lower the cost of calls to destinations beyond the private network, the gateway should also support "off-net" links to the PSTN. In the scenario of the company with offices in London and New York, for instance, if someone in the London office wants to reach an individual in Washington - via voice or fax - the network should be able to make the call to New York via the Frame Relay network, and then go "off-net" at New York to the PSTN for the remaining leg of the call from London to Washington.

SEAMLESS INTEGRATION
Of course, to make sure the system is appreciated and not circumvented by end-users, this sophisticated call handling must occur without their noticing it. In other words, the system should support any existing dialing plan, and no hard-to-remember, unwieldy prefixes should be required when dialing.

To further ensure seamless integration with existing business operations, the gateway should feature an integral billing system that relies on call detail reports. With an ability to collect information on the originator of each call, the digits dialed, the path taken by the call, and its duration, calls can be accurately charged back to departments, a particularly complex and important issue for "off-net" calls. Also beware that unless call detail information is be provided in the form of an ASCII flat file, it will be difficult to utilize with existing billing packages, so reconciling calls in cases where complex paths were taken may be difficult.

MANAGEMENT AND SCALABILITY
To simplify the complex management tasks associated with configuring and maintaining a voice gateway requires a tightly integrated network management system that features a graphical user interface. This GUI should not only be easy to use, but should also have the intelligence to prevent invalid configurations from being established.

Not to be overlooked is the importance of selecting a voice gateway solution that is scalable in terms of both the number of ports each gateway at each location can support, as well as the number of locations that can effectively communicate with each other over the network. The important issue, insofar as the number of ports is concerned, is that configurations exist to meet varying needs within the enterprise. If some branch offices only need four ports, for example, the gateway vendor should be able to provide a solution that features four ports; be wary of vendors who require configurations with excess capacity.

On the high end, capacity should be virtually unlimited. Look for solutions that can cost-effectively support a direct PBX connection via T1/E1. Gateways should be capable of supporting multiple digital interfaces, yielding as many as 180 ports, on a single gateway platform. The ability to seamlessly link multiple platforms will ensure future growth. All features and functionality, including support for frame relay, IP, and Internet, voice/fax transparency, billing, and management should be available to all platforms -- no matter how large or small.

IT COMES DOWN TO QUALITY
And finally, consider voice and fax quality. All vendors tout their quality of service (QoS) mechanisms, such as queue management, prioritization, forward error correction, and jitter buffer management. Some go one step further and feature traffic shaping to ensure that the bandwidth utilized by voice circuits is restricted and never overwhelms the network.

While all of these features are critical, in the final analysis, the most important issue is how good the voice sounds, and how clear and error-free the faxes appear. So, be sure to trial a system and carefully evaluate not only its underlying technology, but its end products as well.

Although there may well be agreement on what constitutes a clear fax, voice conversations are a different matter. How voice sounds to different individuals can be subjective, and unless a broad spectrum of end-users are consulted, universal acceptance of the gateway may prove elusive.

In sum, the convergence of voice over data networks is likely to be the communications paradigm for the 90s and beyond. With robust voice gateways that empower companies to carry voice over their frame relay and IP networks, as well as the Internet, the impact on end-users should be nil, but the bottom line benefits infinite.

Tony Morris is director of marketing for NETRIX. His responsibilities include market development, new product planning, and management of existing products. NETRIX manufactures and markets wide-area network switching products for enterprise networks. The company's products unify voice, data, and image applications over a diverse and ever-changing array of communication services. Combining patented, switched, compressed voice technology and advanced networking capabilities, NETRIX delivers networking solutions that improve network performance and achieve substantial operational savings. For more information, visit the company's Web site at www.netrix.com.