December 2000

BY HENRY DEWING

Internet telephony is revolutionizing telecommunications, delivering benefits like low-cost long-distance calling and fax communications, and offering new and flexible services to improve productivity. At the same time, most mid-sized and large companies already have installed PBXs they aren't prepared to scrap. Fortunately, there's no need to start from scratch to enjoy the benefits of IP telephony. Today, there are several ways in which enterprises can take advantage of Internet telephony without sacrificing their existing PBX investment.

Reaping the benefits of VoIP takes two essential ingredients: products that create value for the enterprise, and people who can correctly implement them. Both ingredients are equally important. You presumably already understand the benefits of IP telephony, but it might be useful to discuss some of the ways in which a PBX can gracefully be brought into the IP network, delivering lower-cost and more flexible services to a broader cross-section of the enterprise's employees.

As the volume of calls between corporate locations grows, enterprises look for ways to lower their incremental cost. One way to do this is by using IP gateways to route traffic over their intranet. By using IP transport to the desktop -- on the opposite side of the PBX from the IP gateway -- enterprises can:

• Install and manage only one network on their premises.
• Provide full-featured PBX service to remote users.
• Easily integrate third-party services.

Once the PBX is surrounded by VoIP connections, the enterprise is in a position to easily migrate to a fully converged architecture.

DEPLOYING VoIP IN THE ENTERPRISE
Telecom managers tasked with converging the enterprise's network have their work cut out for them. Evaluating all the VoIP vendors -- making certain the one you choose will still be around after burning through its IPO money -- is only the beginning of the challenge. It's also essential to ensure the solutions you deploy adhere to accepted industry standards. This is the only way to be certain that today's investment will not be left stranded by tomorrow's interoperability failures.

Unfortunately, making sure your solution adheres to industry standards is not an easy task in the VoIP market. Many standards are still only in the proposal stage, and all of them are being refined at some level. If the PC model holds in the VoIP market, consumers of IP telephony systems will eventually be able to easily combine solution components from multiple vendors. But today, ensuring that components from different vendors are interoperable is a monumental task. VoIP standards include both H.323 and H.225, as well as SIP and MGCP, which ensure that both ends of the call know when to ring a phone and open a channel and how to create a conference call or perform other call control functions. Digitized voice can be compressed in a variety of different ways, and must be decompressed in the same way at the opposite end of the call. Compression algorithms include G.723.1, G.729, and others. There are other standards for silence suppression, fax transport, and a variety of other parts of the market. In other words, buyers beware in this market: not all solutions adhere to accepted standards. Those that do adhere to standards don't necessarily comply with the same standards.

Enterprise telecommunications managers -- being rightfully cautious about risking failure of the corporate voice network -- often trial these IP gateways before making a deployment decision. Frequently during these trials there is a temporarily rapid rise in the demand for packet-switched data connectivity and a slower-than-expected reduction in demand for circuit-switched voice network capacity. Because the test is a trial, employees often make one IP call and one voice call simultaneously to hear for themselves the voice quality during increasing peak calling traffic volumes. In some enterprises, this activity can continue for a surprisingly long time. Remember when e-mail was new and people would send volumes of e-mail as soon as they got a new address -- just to see if it worked?

IP GATEWAY BETWEEN ENTERPRISE LOCATIONS
One of the most obvious first steps to implementing VoIP in an enterprise is by installing gateways to interconnect geographically separate locations. This can be accomplished by using IP gateways and packet transport on the intranet (or VPN over the Internet) to replace existing PBX tie lines. The requirement to maintain voice connectivity and data connectivity capacity to meet peak usage means that both networks are equipped to handle nearly the total telecommunications load, even after the end users quit their tests. There will be smaller incremental requirements for packet capacity when the last voice circuits are turned off than when the first ones are turned off. The same traffic engineering rules -- which favorably affect cost per user as the scale of an installation increases -- hold true whether the transport is via packet or circuit.

A crucial concern when implementing these VoIP gateways is quality of service (QoS). Capacity planning is essential, so network managers must understand and manage their network traffic profiles for both data and voice. Although users become irritated while they wait a few seconds, or even a minute for a large file to download, they go ballistic when a phone call breaks up or is dropped. Since many datacom and telecom departments have been established over the past years, there are many more organizations today that can handle both voice and data than there were five years ago.

Telecommunications managers can ensure reliable voice quality over their packet networks in a couple of different ways. On the intranet, network managers can always increase capacity to preserve voice quality. Telecom managers can also use VoIP gateways with PSTN fall-back capabilities. The best of these gateways sense the delay in communications and seamlessly switch a call between the packet network and the PSTN while a call is in progress.

Many industry participants are working on QoS standards. Implicit in QoS is that the IT manager can assess in advance the relative priority of the CEO's video conference with Wall Street analysts, the SAP data dump to the factory for the quarter's final production run, and a phone call between sales offices to decide where to go for happy hour. The IP Layer 2 class of service bit and Layer 3 type of service bit allow all voice and data to be differentiated across the LAN and WAN, ensuring that neither a fax nor SAP will slow down a voice call on the intranet. Other proposed standards, like RSVP, try to assign priorities to applications and particular communications. How these standards are implemented can have a wide variety of effects on voice quality.

IP GATEWAY WITHIN ENTERPRISE LOCATIONS
There are many options to consider in migrating that last mile to a converged network. Putting voice communications over packet networks between the PBX and the end user requires more equipment to be distributed around the enterprise, making traffic analysis and QoS assurance more complicated. Putting the voice communications on the enterprise LAN allows easy interconnection of the phone system with other client server applications like unified messaging or CTI-enabled CRM applications.

Telephone calls can go from the PBX to the LAN in two different ways. Most large PBX vendors offer IP-enabled line cards. These line cards connect directly to the enterprise LAN, delivering the full functionality of the PBX to the LAN. These cards completely replace existing PBX line cards that connect to the twisted-pair enterprise telephony network. An alternative way to get the telephone calls from the PBX to the LAN is to deploy PBX extenders that connect on one side to the existing ports on the PBX and on the other side to the LAN. Either of these options puts the telephone calls onto the LAN, allowing access to remote users via RAS connections, to make and receive telephone calls as if they were at their desk in the office.

Across the LAN, at the desktop, there are at least three deployment options: softphones, IP telephones, and gateways that put calls back onto twisted-pair connections.

Softphones are telephone emulation programs that run on a desktop computer, delivering a full-featured telephone set emulation to end users. If end users are comfortable depending on their PC to make telephone calls, this requires the least incremental investment.

Deploying IP telephones is costly, since the price of these sets is still generally high. IP phones connect directly to the LAN. Some have a two-port hub, enabling users to plug their PC's network interface card into their phone for connection to the LAN. These sets are becoming more sophisticated, with some offering Web browser capabilities and access to other corporate data in a more traditional client/server fashion. Most of these phones require one connection to the LAN and another to external AC power. There is a proposed IEEE standard to allow the delivery of power to these sets from routers on the LAN via CAT 5 cable.

Using gateways to return telephone calls to twisted pairs allows enterprises to maintain their investment in existing digital or analog telephones, while requiring the IT department to maintain twisted-pair connections from the wire closet to the desktop. Some more sophisticated gateway pairs pass all the features of digital PBXs to their digital telephone sets just as if they were directly connected to the PBX.

BRINGING IT ALL TOGETHER
Ultimately, telecom managers need a compelling business case to undertake the risk associated with deploying a new architecture for their telephone systems. While cost savings may get the accountants' attention, the executive staff will be most interested in how this creates competitive advantage for the enterprise.

An open implementation of VoIP allows great flexibility, enabling rapid deployment of new services that will allow employees, customers, and suppliers to interact more effectively using applications that can now easily interact with voice communications systems. This means there will be little tolerance for failures in interconnecting voice and data systems, since these are crucial corporate systems. This deployment will require converged skills on the part of IT staffs and VARs who will deploy and maintain these solutions. Not only will the staff need to understand why and how to configure an ISDN line and a 100 MB switched LAN, they will also have to evaluate the relative priority of digitized voice versus traditional data traffic to implement QoS that serves the interest of the enterprise. This is no small task, but it's one that all of us in the industry depend on for our own success.

Henry Dewing is senior enterprise marketing manager for Dialogic Corporation (an Intel company). 

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BY EDDIE LAMBERT

The merger of data and voice communications has offered great advantages for large business. The merger of the Internet with traditional telephony has allowed these businesses to improve communications, cut long-distance phone costs, and simplify IT management, but smaller enterprises have been left out in the cold because the technology is too expensive. Migrating from the old-fashioned, circuit-switched key systems and small PBXs to an Internet protocol (IP)-based telephony system used to cost big bucks, but fortunately for small and medium-sized businesses, that's changing, allowing these organizations to gain revolutionary benefits with manageable costs.

New technology is making this possible. Traditionally, migrating to this new technology platform consisted of replacing existing voice equipment. However, the costs for the new equipment and needed training made this alternative inviable for most small to medium-sized businesses. The new technology, an IP-enabled PBX, allows these enterprises to use existing network infrastructures to hook up traditional PBX-based networks with IP-based networks. As a result, small businesses don't need to change existing cabling or handset infrastructure. Instead, easily installed software can upgrade the existing PBX, transforming it into an IP-enabled PBX -- allowing the organization's core voice system to speak IP telephony protocols. PBX users will also be able to speak with other IP telephony users as the solution proliferates.

External VoIP gateways or integrated IP boards can enable existing PBXs to become IP-enabled voice platforms, allowing smaller organizations to take advantage of the data network to deliver telephony benefits across the enterprise. Because IP-enabled platforms run on easy-to-use data networks and use Windows or Web-based user interfaces, rather than the traditional complex proprietary configurations and maintenance tools, these new products can offer enterprise features to employees that even traditional PBX systems could not deliver. These new technologies have replaced the circuit-switched or serial connections between traditional communications devices. As a result, these IP connections enable management applications to reside anywhere in the network.

Businesses can then use standard tools and operating systems to monitor and configure the system from anywhere within the network, which could be in the same building or across the country. In addition, one of the biggest advantages of moving to an IP-based communications system is the drastic reduction in costs for long-distance calls. The move to an IP-based system cuts phone costs by simply bypassing the public phone network and routing all inter-office long-distance calls over a wide-area network, instead of the traditional phone network. For example, Business A employee in San Jose wants to call Business A employee in the New York office. Now, with an IP-enabled system, the employee just dials the New York number as another extension number in the inter-office system and gets to talk to the New York employee, but without the hefty phone costs that would occur over traditional circuit-switched phone lines.

THE NEXT STEPS
There are new products on the market that take this scenario even further. For example, simple desktop gateways can allow businesses of any size to seamlessly connect mobile/remote offices into the main office iPBX system. Telecommuters in the company can be outfitted with normal phones and use the IP connection to the central office for their phone calls. This allows the remote user to have central site PBX services in their home office or remote branch, and wherever the user goes, the PBX services will still be the same. In addition, because companies are no longer dependent on physical wire connections, they will no longer have to deal with expensive leased lines. With the use of these desktop gateways, companies can open a branch office without investing in a costly new PBX system, or training staff and technicians on a new system. Instead, the branch office phones can be seamlessly connected via the desktop gateways to the main office iPBX system.

For instance, Joe is at home working today. Now any call coming into his main office extension will automatically ring at his remote office phone as well via the corporate IP network, without the caller being aware of it. In fact, wherever Joe works, he will still be connected to the main PBX and all of its capabilities. That's because the data network knows how to send his extension address to any location with a phone with that same data address. And wherever Joe takes his phone, he still has access to his voice mail, central operator services, corporate directory, PBX features, etc.

Another feature that's a recent addition to this unfolding IP telephony world is unified messaging (UM). This new feature allows anyone accessing the system to read and hear e-mail, faxes, and voice mail from any terminal, be it PC, land-line phone, cell phone, or PDA. The software essentially allows you to send or receive your communication in any form you choose. For example, if someone sends you an e-mail, you could retrieve the message over your phone using text-to-speech technology. Or you can view a fax over your computer.

The migration towards IP telephony with an IP-enabled PBX is just the first step into a whole new world of technological advances that are putting voice and data all into one system. But, for a small to medium-sized business, this first step to a converged network opens up a whole realm of possibilities for new services and functions that previously were only available to large corporations.

Eddie Lambert is VP of product development for Ericsson Enterprise Systems. 

[ Return To The December 2000 Table Of Contents ]