February 2001

BY ALLAN ZANDER

Both industry and consumer interest in simplifying voice and video communication over the Internet has skyrocketed. Each month, more Web sites are dedicated to improving these technologies. Buzzwords like "speechweb" are becoming household names in the high-tech homestead. Until now, the implementation of telephony features (dial tone, call waiting, forwarding, messaging, hold, etc.) has remained the exclusive charge of proprietary enterprise voice companies. Built and sold as large, whole systems, voice solutions employed proprietary protocols that made use of unique coding and transmission standards. While the recent move toward developing open and universal voice communication standards over existing Internet protocols promises remarkable benefits for manufacturers, carriers, and individual users, the full potential of IP telephony will only be realized through the extension of its benefits to the working world -- the enterprise customer.

WORKPLACE GAINS: TRANSLATING STANDARDS INTO SOLUTIONS
The implementation of IP telephony standards makes building a voice-over-IP (VoIP) network an attractive communications option for enterprises. Gains resulting from the institution of industry-level standards are notable, and include:

Increased service options, enhanced features -- Major enterprise PBX products generally include many hundreds of features and highly reliable call control. The general architecture for making these features possible and for providing the call control comes from a master/slave approach. The end devices in an enterprise solution are dumb -- whenever a feature needs to be added or enhanced, the entire code for the PBX must be modified and verified. With this approach, adding or enhancing features can take years. Open standards on IP give the PBX freedom, allowing software to reside elsewhere on the network and greatly simplifying the feature's development.

Increased compatibility/interoperability -- The switch from proprietary to standard protocols frees manufacturers from the constraints of PBX-specific design, which will significantly expand the number of manufacturers producing individual IP telephony components. The resulting variety of components will allow enterprise customers to build their IP telephony systems and comparison shop for the various interchangeable, plug-and-play components of their choice, increasing the attractiveness of the solution.

Reduced costs -- Open standards allow enterprise manufacturers to simplify telephony products and devices by reducing the amount of memory and power that they require. When simpler products are paired with increased competition in the vendor market, costs should plummet.

Increased flexibility -- The acceptance of quality standards allows the enterprise customer to assess their business requirements and select the appropriate standard based on their unique requirements and priorities. For example, while SIP may enable fewer features than other protocols, its cost-efficiency and low processing requirements make it attractive when controlling the component costs of the product.

Faster processing and information transmittal -- Standardized voice, control, and telephony feature programming signals will not only provide the means for audio and video signals to move as data between IP-addressable components, but enable manufacturers and research organizations to improve and advance programs to interpret and process these signals more efficiently, and bring more R&D resources to the table. IP addressing will also enable remote, shared, and consequently more powerful computers to control voice communications.

Increased user proficiency -- The more familiar the tool, the higher the level of proficiency. When tools are easier for end users to use, their productivity rises, to the ultimate benefit of their employers.

AN APPEAL FOR STANDARDS
Prior to the introduction of standards, the IP telephony world was a cacophony of competing voices, a choir of dissonant soloists haphazardly thrown together, more comfortable singing in isolation. Stand-alone, incompatible proprietary protocols required both parties in a conversation to use the same products to communicate. Given their self-contained intelligence and independence from a central switch, IP phones and devices were complex and costly. As VoIP gained in popularity, it became evident that its full potential would only be realized with the development of cost-effective, interchangeable, flexible PBX solutions. And so telephony standards were called to impose harmony on the choir. The challenge: create standards that recognize (address) all current devices and that are:

• Open-ended, to recognize the not-yet-invented devices of the future.
• Able to accommodate the quantity of those devices as they are developed.
• Robust enough to recognize and communicate all features offered by each device.
• Simple enough to be understood and used by the entire manufacturing industry.
• Logical and consistent, to provide a foundation for a simple, accessible user interface.

THE PILLARS OF PROTOCOL
The mechanisms necessary to enable end systems and proxy servers to supply a variety of features to enterprise customers are provided by the four main pillars of IP telephony protocol (see Table 1 for more details):

• H.323: The longest standing telephony protocol, H.323 is used to define the parameters of audiovisual conferencing and data transmission across networks.
• Session Initiation Protocol (SIP): SIP is a lightweight, text-based signaling protocol used mainly to establish, modify, and terminate voice calls.
• Media Gateway Control Protocol (MGCP): MGCP is a data signaling protocol used to transmit primarily audio signals over the Internet and other packet networks.
• Megaco (H.248): An enhancement of MGCP and an offshoot of H.323, Megaco is a call control protocol that supports a broader range of networks, has substantial trunking capabilities, gives IP networks tight connectivity, and allows for faster call routing.

Table 1

A PATH TO PROGRESS
Given its benefits, it is not surprising that efforts made to establish IP telephony on the telecommunications stage enjoy formidable industry support. Standards allow IP telephony technology designers and manufacturers to use their products interchangeably, develop new features faster, cheaper, and better than in the past, and expand their product options. Future features will be derived from features available on residential lines -- features like the SS7-built *6 functionality will eventually be available to enterprise customers directly through their IP-PBX.

The Institute of Electrical and Electronics Engineers (IEEE) facilitates the standardization efforts undertaken by industry and other players. Scheduled bake-offs -- conferences attended by members of all four standards committees -- provide a forum for comparing and contrasting technologies, assessing progress, and resolving conflicts. The union of the North American-based Comité Consultatif International Téléphonique et Télégraphique (CCITT), and its parent company, the European-based International Telecommunication Union (ITU), reflects the direction toward a worldwide set of telephony and other communication and infrastructure standards.

TRANSFORMING COMMUNICATIONS
IP telephony solutions, made increasingly reliable and accessible through standardization, have the potential to completely transform the ways in which enterprises communicate and make use of the systems that enable communication. The combined efforts of manufacturers, researchers and developers, and other players are laying the groundwork for a telecommunications revolution from which enterprises will reap great rewards. The development and implementation of standards represents a significant commitment to making the technology simpler, more efficient, and accessible.

Allan Zander is director of product marketing, Destop Peripherals and Applications for Mitel Corporation.

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