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August 1999

An IP-PBX And CT Server Enable Smooth Internet Telephony Transition


Today, you’re closing a big deal. You’re looking feverishly for your lucky pen — the one you always use to sign contracts. You look everywhere, even moving the phone, which is tucked into the corner of your desk. As you move the phone, you see a fat red cable connected to the back. There’s no RJ-11 port. What’s going on here?

What’s going on is that you’ve been talking over an Ethernet cable since the day you started at your new company, without even realizing it. “Is the Internet telephony hype getting to me?” you ask yourself. “Am I dreaming?” You thought Internet telephony (IPT) was really just about rate arbitrage opportunity and “free” phone calls. While rate arbitrage opportunities have certainly been the driving force behind the development of the IPT industry over the past three years, the cost-of-ownership benefits IPT systems offer — for both infrastructure and network management — are its real sustaining advantage. This is true for IPT in both the public network and the enterprise.

Traditional PBX vendors such as NEC, PC-PBX vendors such as Comdial, and some newcomers such as Selsius (now part of Cisco) have already demonstrated — and begun selling — either pure IP-PBXs or IP-enabled PBXs that connect to H.323-ready Ethernet phones. These phones look and act like the standard, proprietary, digital, feature phone that’s already on your desk.

What has driven the need for an IP-PBX? Companies like StarVox   have been selling IPT to the enterprise as an adjunct to existing PBXs, taking advantage of intranets that had been set up between headquarters and remote offices before IPT was even a dream. The installed PBXs work, and work well, so they are not going away. Enterprises can, however, take advantage of rate arbitrage opportunities by installing IPT gateways in each enterprise location to send both voice and fax calls over the intranet to their own locations.

Fax is a big driver for IPT in the enterprise. About 70 million fax machines are in use around the world, many in business environments. These fax machines exist, will continue to be used, and are not IP-enabled. Approximately 40 percent of most corporations’ telephone charges come from the cost of sending faxes. There is still a need to use these fax machines as endpoints, and there is also a need to send real-time faxes (T.38 is the real-time fax standard for H.323 environments). So, why the need for an IP-PBX?

It comes back to the infrastructure and network management cost savings. An IP-PBX requires only one wire to the desktop. Since companies already need to install Ethernet for computer connectivity, the MIS department can enjoy tremendous cost savings if it doesn’t have to install a separate voice infrastructure. Also, when Ethernet is the only infrastructure needed, system management is much easier. The MIS department only needs to manage the data infrastructure — which can now carry both voice and fax.

While the PBX adjunct system certainly fills a large enterprise market need — especially for Fortune-2000-sized companies — there is still a tremendous need it doesn’t fill. The IP-PBX is a great way for these companies to grow their infrastructure and add capacity.

Say you are the MIS director of a company expanding into a new building. An IP-enabled PBX would certainly be less expensive, from both an equipment perspective (the PBX and the cost of each proprietary digital feature phone) and an infrastructure perspective. Using this reasoning, small to medium-sized companies could start out with only an IP-enabled PBX. While each of the IP-enabled PBX vendors mentioned earlier has H.323 phones to sell with its PBX, H.323 fax machines are not yet available — although they are on the way. When H.323 fax machines enter the marketplace, IP-only PBXs may be able to replace IP-enabled PBXs.

Consider the voice and data network needs of a typical company. Most enterprises have a proprietary PBX as the centerpiece of the voice network. There are also usually adjuncts connected to this PBX, typically open systems-based computer telephony (CT) systems. Each of these systems is a standalone server, with its application tied to the computer-telephone integration (CTI) hardware (Figure 1).

Figure 1. Enterprise Media Today
dialogic1.GIF (33937 bytes)

Some of these systems may also be connected to the data network. For example, the fax server is connected, since you may be able to send faxes from your desktop computer to a fax machine at another location. Alternatively, the fax server may need to fax back a document (stored on the data network) when a caller request comes into the fax server. If you have an IPT voice/fax gateway, it is also connected to both the voice and data network, bridging the two by converting one transmission medium to the other. Also, most enterprises also have a remote access server (RAS), typically to accommodate employees who need to dial in to the e-mail system, or who need access to a database.

Bringing together all the adjunct servers into one system (which is not as hard as it might seem, since these servers are typically based on open systems), makes it much easier to create applications and manage resources (Figure 2). Applications can focus on their differentiating features instead of having to manage low-level resources. The CT server software takes care of all underlying resource management, and the application has no need to know the various voice inputs and outputs (for example, digital, ISDN, analog, H.323, MGCP). It only needs to know that a call is to be made or received. The type of signaling and the transport mechanism are transparent to the application. The CT server means less work, and much more portability for application providers. For example, a CT server application could automatically move into the IP network world from a pure voice network world if a resource manager layer were there to handle the underlying transport.

Figure 2. Multi-Application CT Server
dialogic2.GIF (29298 bytes)

Now, consider again the IP-enabled PBX scenario. If the CT server and the IP-enabled PBX merge, all the voice needs of the enterprise are run from the CT server, which is now very IP focused. This IP focus does not lessen the importance of the enhanced services expected from the voice side. In fact, these enhanced services are just as important — if not more so — in the IP world, since the compression algorithms make features like play/record, fax, conferencing, DTMF detection, fax tone detection, caller ID (even when coming in from the outside instead of intra-enterprise), and speech recognition even harder. While a pure router gateway has its place, enhanced services are a crucial part of the IP-enabled PBX.

So, if you are an MIS director, think how easy it would be to add a new employee if your company had an IP-enabled CT server. Performing a single directory and administration operation would provide all the phone and remote access services your new employee would need. And if you are a new employee, or working in a new building, turn that phone around to see what kind of connector is on the back. You might just be surprised.

Jim Machi is director of product marketing, Internet Telephony, for Dialogic Corporation. 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. The company is headquartered in Parsippany, New Jersey, with regional headquarters in Tokyo and Brussels, and sales offices worldwide. For more information, visit the Dialogic Web site at www.dialogic.com

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