July 1998

BY MARGARET ANN CHAPPELL

The first commercially available Internet (IP) telephony system was introduced in early 1995, and was quickly followed by more than a dozen products later that year. These nascent systems were software applications running on multimedia PCs with connections to the Internet. They were enabled by several factors: advances in compression technologies, increased PC processing power, the emergence of multimedia PCs, faster modems, the ubiquity of Internet access, and industry innovation in applications. To complete an IP telephony call in the early days (three years ago!), calls needed to be prearranged. Both parties needed the same software, the caller needed the callee's appropriate IP address, and the called PC and software had to be on and online when the caller "dialed." This voice over IP call was essentially free, though its costs were high in patience dealing with poor audio quality, and inconvenient call setup.

GATEWAYS CHANGE EVERYTHING
IP telephony has since moved from hobbyists to a revolutionary technology in the telecommunications industry. Phone-to-phone calling across IP networks, and the advent of Gateways between the public switched telephone network (PSTN) and IP networks triggered this transition.

Gateways made using the IP network almost transparent to the caller. The initial complex addressing problems were resolved, because the caller could now use conventional phone numbers. And by using a phone instead of a PC, some delay could be eliminated. Incoming call notification was easier - the phone would ring to alert the called party. An immediate interest in moving fax calls to the IP network (particularly in the international arena where a large percentage of traffic is fax) also developed. Dedicated packet-switched fax networks, typically run over frame relay, had preceded the emergence of IP telephony. But soon, proprietary voice over IP Gateways began supporting the transport of faxes, allowing fax traffic to take advantage of the more cost-effective IP network.

TODAY'S GATEWAY
Today's Gateways are powerful PCs or workstations that convert the call control and media from a circuit-switched world (PSTN) to a packet-switched world (IP), and back. Gateways typically employ more processing power than desktop PCs, so they are able to compress audio faster and run more sophisticated fax, modem, echo cancellation, and packet recovery algorithms, all of which contribute to significantly better quality.

Low-end Gateways (one to six ports) normally use the main processor, typically a high-end Pentium chip, to provide the media processing, call control, and packetization. The performance of these Gateways is limited by the CPU's processing power and the need to share the PC bus. Thus, delays increase dramatically as the traffic increases. Adding digital signal processor (DSP) subsystems to provide media processing can increase performance. Today's state of the art Gateways based on CTI platforms can support up to 100 ports. High latency and limited port density, however, are still limiting factors.

Gateways today need to provide more services than just the obvious call control and media conversion. Companies deploying Gateways need to bill for Gateway services, which necessitates an authorization system and the maintenance of billing records. The terminating Gateway must be located, which creates a need for directory and routing functions to find the appropriate Gateway and its IP address. Today, most of these services are provided in a proprietary manner - a company deploying an IP telephony service relies on one vendor for all of its equipment.

In many ways, the current generation of Gateways is similar to the initial IP telephony systems - only now it is the service provider dealing with interoperability and reliability issues. Most Gateways today are proprietary systems: They require the terminating and originating Gateway to use the same software, and they have their own methods for authentication, routing, billing, and other administrative functions. Voice quality has not achieved "toll quality" on a regular basis. It is still plagued by delays and echoes, which are often attributable to poor network engineering or load balancing on the Gateways. Gateways are not as reliable as they need to be.

MOVING TO THE MAINSTREAM
How will Gateways move into the mainstream? Several factors are essential to make this transition. First, reliability is critical. Today's CTI-based Gateways were never designed to provide the reliability needed to offer a high-quality public IP telephony service. Second, Gateways must be interoperable. Customers expect to call anyone, anywhere, anytime. The third critical feature is seamless network management. Service providers must design and maintain their networks in order to provide an acceptable quality of service. These characteristics are all components of what has come to be known as "carrier-grade" Gateways, the next generation of Gateways.

Reliability
Carrier-grade Gateways are being designed for scalability and reliability. They will have built-in redundancy, so that spare subsystems are automatically engaged if a subsystem fails. They will have run-time self-diagnostic hardware that can detect failures such as a faulty processor, and seamlessly switch to a backup. They will have hot-swappable boards that allow fault corrections and upgrades without taking the Gateway out of service. As part of the drive toward reliability, carrier-grade Gateways will be tied into a service provider's network management scheme for remote management and diagnostics, which will require SNMP (Simple Network Management Protocol) agents and MIBs (Management Information Bases). As traditional carriers enter the market, they are demanding NEBS (Network Equipment Building System) compliance - a testing standard written by Bellcore for equipment suppliers - and the reliability associated with their traditional voice networks.

Interoperability
Adhering to standards and enforcing interoperability between products from different vendors has assumed increasing importance as service providers demand multiple sources for their equipment. Achieving full interoperability in the IP telephony environment will require cooperation between vendors, as exemplified by the IMTC (International Multimedia Teleconfer-encing Consortium)-sponsored H.323 Interoperability Events. With the recent acceptance of version 2 of the ITU H.323 standard, the market should see more movement in this direction. Work on version 3, currently underway, will include standards-based real-time and store-and-forward fax transmission under the H.323 umbrella. H.323 is widely regarded as the suite of standards that will drive IP telephony to ubiquity, since different service providers will be able to cooperate and offer broader coverage than individual providers will. Clearinghouses to facilitate this cooperation are already emerging. Meanwhile, SIP (Simple Internet Protocol), an alternative standard being considered by the IETF, is lagging H.323 in terms of its acceptance and the scope of issues that have been addressed to date.

Network Management
Another important change necessary to make IP telephony successful is more centralization of the network intelligence. Current Gateways are unduly expensive and difficult to integrate into a multi-vendor environment. They contain varying levels of intelligence that are duplicated in various places in the network. The H.323 standard defines an entity known as a Gatekeeper that is designed to provide many of the services that are currently found in Gateways - such as authentication, routing, and address resolution. Like Gateways, the H.323 Gatekeeper will need to be carrier-grade in order to be considered a viable component in high-quality network implementations.

The Gatekeeper is poised to become the intelligence of the IP telephony network and perhaps more importantly, the link to the legacy billing, network management, and operation support systems that represent years of effort and investment. When people talk about quality of service in reference to IP telephony, they are commonly referring to audio quality or bandwidth reservations. However, quality of service in a broader sense is being able to run the network efficiently, engineer it, have a seamless transition to an alternate route should problems arise, accurately bill for services, and offer leading edge services.

A particularly important Gatekeeper component will be an interface to the SS7 network. This linkage will allow IP telephony services to incorporate many of the services available today on the PSTN without duplicating the infrastructure needed to provide those services. This linkage will be another step in the transparency of IP telephony service to the caller. Connections to the SS7 network will allow call redirection services such as 800 and local number portability, as well as calling card billing, to be offered to IP telephony users.

In addition to becoming carrier grade, Gateways will begin to add more functionality. As DSPs become more powerful, data modems will become fully integrated into the Gateways such that a single Gateway can handle data, voice, and fax traffic. Other services will include video conferencing, white boarding, etc. The combination of these new services will enable the true driving force behind IP telephony - richer services, and true multimedia communication.

MOVING TO EVERYDAY USE
Where does the future for Gateways lie? Gateways will continue to evolve, becoming more reliable, cheaper, and having higher port densities. The Gateway functionality will gradually be integrated into a wide range of devices such as PBXs, switches, routers, mobile systems, and remote access servers. This migration will be facilitated by today's movement of intelligence from the Gateways into other network entities, network management systems, and operation support systems. However, the adoption of standards and resultant interoperability is critical for this evolution to occur.

Ultimately, the distinction between circuit-switched and packet-switched networks will fade for end users. There will be well engineered and managed IP networks that share services and resources with the PSTN. The window of cost differential between the traditional PSTN and the IP network is rapidly closing (and will close even more quickly if access charges are levied on IP telephony providers).

The window of opportunity for new innovative services is opening up. It will be easier, faster, and cheaper to offer innovative services in the IP telephony environment than in the traditional circuit-switched environment. New services will arise from the innovation that is traditionally associated with the Internet. Ultimately, customers will benefit because the new services will not only be richer in functionality, but will be more easily tailored to their particular needs. In the end, that is what drives a technology into the mainstream.

Margaret Ann Chappell is a Distinguished Member of Technical Staff at elemedia. elemedia, a wholly-owned software venture of Lucent Technologies, is a leading provider of H.323-based software toolkits that enable high-quality solutions for Internet telephony and multimedia communications. elemedia's Gateway and Gatekeeper toolkits enable our customers to develop complete IP telephony systems without sacrificing speed to market. Developed by engineers with years of experience in the technologies required for sophisticated telephony networks (e.g. network management, SS7, billing), elemedia's products link today's networks with tomorrow's, while promoting standards and interoperability. For more information on elemedia, visit the company's Web site at www.elemedia.com.

BY SEAN PARNHAM

With technological capability just intersecting the critical mass of economics-driven demand, the IP telephony industry has left the garage hobbyist stage. Still, its "industrial-strength" era remains on the horizon. Today's voice telecom industry bears enough resemblance to the data networking environment of fifteen years ago that it's worth examining history to avoid the miscues of the early '80s data networking explosion. The Internet lesson for today's vendors is to listen to the echoes of consumer voices from the earlier era - consumers want open platforms, highest performance, and lowest cost.

SALIENT SIMILARITIES
This generation of technologists has realized the benefits of standardizing on a minimal set of interoperability specifications early on to launch the IP telephony marketplace. This is where the "parallel universes" metaphor diverges. But, consider the similarities.

Both marketplaces, for instance, were initially dominated by mainframes. Put an IBM 3x0-class mainframe beside a 5ESS or Tandem class telco switch and they look like "big iron" twins - both extremely expensive, controlled by priesthoods of employees monitoring and maintaining them from glass houses, and offering far too few choices for most consumers.

Add to this the similarity that both today's telephony infrastructure market and the earlier generation's data networking market faced a non-linear amount of change. Moore's Law, which predicts that the density (and power) of computing doubles every 18 months, forever changed the face of computing. This force is now about to collide with an immovable object - today's telecommunications industry.

PAST PERFORMANCE
In the past on the data side, this force created innumerable opportunities - new markets, and new choices for consumers. It rolled right over players too slow to recognize the change and too late with too little to respond to it. But it was not so much a disruption of an old industry as it was an explosion of a new one.

Mainframes remain very much a part of the enterprise world today, harboring legacy data and being rejuvenated for new and more efficient uses. Significant advancements eventually emerged in the data networking realm. Who could have predicted the wonders of the Web fifteen years ago? We can likewise expect these advancements to arise in the telecommunications arena - but more swiftly.

In fact, just as there was an explosion of competing computing platforms erupting from data's big bang, expect a steady mushrooming of different telecommunications platforms in the near future. Carrier-class switch manufacturers will be injecting voice over IP capability to break open their switches. Entrenched data players are already putting voice over IP functionality into their products.

EMBRACING STANDARDS
The current industry has seen the wisdom of standards such as TCP/IP, HTTP, and HTML to secure interoperability positions between various vendors. Today's new age telecom market has not immediately balkanized - as did its predecessor's - provoking customers to delay deployments. This is good, but customers must be vigilant to match standards-based IP gateways with applications as the price/performance competitive curve takes its course.

Today, the data world is extremely horizontal, dominated either by de facto standards toward which customers have gravitated, or by a few, mandated open standards - a lesson it learned slowly. Meantime, the traditional telephony world is a big, closed, vertically integrated industry. Its IP telephony successor doesn't have to repeat this pattern, and must be leery of vendors who believe they can do everything for everyone. The technology lesson that must be repeatedly learned, it seems, is that it's very difficult to put everything into one platform. Variety with interoperability drives performance and open choices. The incumbent telephony vendors are being joined by a variety of fast-moving competitors. History shows interoperability means more power and more choices at a lower cost.

Sean Parham is director of Motorola's Information Systems Group, Internet Products Operation (IPO). IPO is dedicated to developing high performance IP telephony solutions. Motorola VIPR is a powerful line of IP telephony products that enable real-time voice and fax communications over the Internet or private intranets. VIPR is a part of Motorola's market-leading Vanguard family of network access devices. For more information, contact the company at 512-370-4002 or visit their Web site at www.motorola.com/vipr.