Posted: 03/1999
Serving Up the "Open" Network
By Gary L. Andresen
Over time, advances in switching technology have resulted in smaller, increasingly robust systems that displaced earlier manual, electro-mechanical, solid-state and, most recently, digital switching architectures.
The architectural types that experienced broad acceptance during the evolution of telephone switching systems are generally categorized as manual cord switchboard, step-by-step, crossbar, solid-state, stored-program control, digital-switch matrix and personal computer (PC)-based (see Figure 1).
Figure 1: Telephony Switch Evolution
During this evolution, companies were ultimately given the choice of buying telephone equipment rather than renting it perpetually from phone companies. This early era of "interconnect" resulted from the famous Carterfone decision in 1968. As the "interconnect" industry gained momentum and success, the base of systems available for replacement grew smaller. Telephone system purchases usually resulted from company moves, expansion needs and/or perceived value based on increased functions.
The functionality of stored-program control systems was based on software, so just about any feature conceivable could be programmed into them. The primary limitations then became system-processing power and memory.
The next step in the evolution process was to digital "circuit" switches, which in their original form represented the last of the monolithic system architectures. Distributed architectures followed several years later, enabling remote modules to deliver the same functionality to end users at distant locations as those using the main system equipment.
The next phase was the introduction of PC-like private branch exchanges (PBXs). Since PC components were used, systems were somewhat smaller, but in reality they were still just miniaturizations of previous systems instead of the predicted "paradigm shift" to new open telecom platforms (PC-PBXs) that was being predicted at the time. Dead-end architectures with inadequate long-term flexibility for end users, and the inability of integrators and value-added resellers (VARs) to readily use them to provide solutions-oriented offerings to their customers resulted in the very limited success of these early PC-oriented products.
Such products fell short of meeting evolving market needs because they essentially were just smaller versions of PBXs or automatic call distributors (ACDs) housed in a PC-type cabinet or, in some cases, shelves installed within the same "skins" of existing systems. This approach did not and still does not provide the critical elements needed to advance to the next architectural model, which in many circles is now identified as a telelcom or communications server. Elements of true telecom servers include:
* An open-system architecture that enables third-party applications to control the system via industry-accepted application programming interfaces (APIs)/standards and availability of API extensions to allow expanded call- and voice-processing control in the absence of standard API offerings
* The ability to mix and match hardware elements to meet the specific needs of individual customer environments
* The use of an industry standard operating system that supports local area networks LANs, with the ability to mix-and-match software applications to meet the specific needs of individual customer environments.
From CTI to CT
Figure 2 depicts a computer-telephone integration (CTI) environment where one or more computer systems are integrated to provide a total solution at a single site.
Figure 2: Multisystem CTI Model
This normally is accomplished via the use of communication links between applicable computer and switching systems, which are used to pass status and control information between the systems. This "integrated multisystem environment" is used because historically it has been the only way computer databases-related applications and "closed" legacy switches can be coupled. This results in costly duplication of hardware and limits flexibility of single-site solutions.
Today's computer model is quite different. Individual computers customarily are connected via LANs to support applications such as e-mail, file-sharing, printer-sharing and more. However, individual PCs, workstations and servers are quite capable of running multiple applications simultaneously. Applications can easily pass information to each other at the software level by using technologies such as object linking and embedding (OLE), common object model (COM) and the more recent distributed common object model (DCOM).
The "multiapplication platform" model (see Figure 3) not only allows hardware and software resources to be used much more effectively, but also provides the flexibility needed to allow components to be mixed and matched to best meet user requirements.
Figure 3: Multiapplication Computer Telephony Model
In smaller businesses, branch offices and/or departments, system designers may choose to put everything in a single server. As more users are supported, and/or where resource intensive applications are used, it makes better sense to dedicate machines to specific tasks. Instead of being locked into configurations dictated by proprietary system manufacturers, companies now can choose what makes most sense for them in both the short and longer term.
Manufacturers of "telecom server" class products make single-site CTI easy and affordable by following the computer networking model and supporting "open" system architectures. These systems customarily provide full PBX functionality plus auto-attendant, voice mail and e-mail as well as ACD. The sophistication of the ACD features on these systems is based on targeted markets and the size of the systems being offered.
Desktop CTI
There has been discussion for years about desktop telephone sets for business applications in the future and whether they will migrate into the desktop PC, be connected to the new NT-based telecom servers or connected directly to the LAN. Studies from Dataquest, a San Jose, Calif.-based Gartner Group Inc. company, and others indicate that while users look forward to the benefits of CTI and Internet telephony, they are not ready to abandon the desktop telephones they have grown to love based on convenience and reliability issues.
Another important issue, however, is the high cost of the proprietary phones used with legacy PBX systems. As CTI is implemented on the desktop of regular users, the demand for expensive proprietary phones with large liquid crystal displays (LCDs) and an abundance of programmable keys will disappear unless a new model with lower "commodity pricing" appears. The likelihood of analog sets becoming the phones of choice for use with telecom servers gained further momentum in 1997 as universal serial bus (USB) motherboards, computers and telephone peripheral offerings began to appear. Caller ID USB phones began appearing in the latter part of 1997 and offer an alternative to expensive proprietary sets, especially if used with telephony client software in conjunction with telecom servers. While these sets can be used to support CTI desktops without the need for proprietary telephones, they do not support multiple station-line appearances on a phone via a single port on the system, as do proprietary station sets.
A new type of phone began to appear in 1997 that uses IP technology and connects directly to the local LAN. Initial versions offered by Dallas-based Selsius Systems Inc., which was recently acquired by San Jose-based Cisco Systems Inc., and others use some proprietary protocols, but standards bodies are working towards a common standard that will allow transmission control protocol (TCP)/IP phones to be used across platforms on a commodity basis. When this occurs, expensive proprietary phones designed to work with a single manufacturer product will be a thing of the past.
Shortly before then, in 1995, a small Israeli company called VocalTec Communications Ltd., Herzliya, began offering a consumer product called Internet Phone. It digitized and packetized voice streams and transmitted them to another Internet Phone user across the Internet. This provided the first free telephone calls triggering the beginning of the voice communications revolution. The quality of these calls was subject to Internet delays and was not comparable to conventional telephone quality, but it was free, and that started the voice over "X" (VoX)--the "X" meaning any kind of data network--drive.
Following the release of Internet Phone companies such as Inter-Tel Inc., Chandler, Ariz.; Lucent Technologies Inc., Murray Hill, N.J.; NetSpeak Corp., Boca Raton, Fla.; StarVox Inc., San Jose, Calif.; VocalTec and others saw the need and opportunity to build a voice gateway that would connect with the PBX and send telephone calls over the Internet or corporate intranet. Within a year there were several companies offering network telephony gateway products that used the Internet, intranet or an extranet to lower telephone call costs.
What is Network Telephony?
Network telephony provides the first major change in voice telephone communications since the emergence of digital voice communications in the 1960s. It provides full PBX functionality with public switched telephone network (PSTN) reliability across corporate data networks.
Traditional telco voice networking has evolved over the years to be the most reliable and resilient network services available anywhere. When the electricity is out, the telephone still works. Traditional telco voice networking uses expensive bandwidth inefficiently, and usage fees are assessed on the basis the usage minutes or by the mile.
Network telephony uses modern efficient packet-based networks and provides the means to concurrently communicate data, voice, video and other forms of data over a single, converged network connection. A growing variety of VoX technologies are moving conventional voice telephony onto data networks and providing a convergence of traditional time-division multiplexed (TDM) traffic with data networks.
Enabling voice communications on packet-based networks provides a wide range of advantages over conventional TDM-based public switched telephone network (PSTN) communications. There are compelling toll savings that can cost-justify the implementation of network telephony, particularly if there is international calling.
Network telephony can easily packetize one hour of voice into approximately 2 megabytes (mb) of data.
Network telephony integrates with existing PBXs through CTI. This preserves and extends the corporate investments that have been made in telephone systems and equipment while providing many new PBX-like features that can enhance worker productivity greatly. This productivity provides another substantial cost savings while avoiding PBX replacement to obtain the new features.
Enhanced features in some products include caller name display, call disposition screens, corporate white pages, intelligent rules-based call forwarding, on-net and off-net dial plan support, guest office support, telecommuter and mobile-worker support. Additionally, there are automatic reliability features that will dynamically route calls and fall back to the PSTN when network bandwidth is unavailable.
Corporate Network Telephony
Corporate or business-to-business use may well become the single most important growth factor for network telephony. Most corporations currently use some form of wide area network (WAN) connectivity for e-mail and file transfer between their offices. These WANs are rapidly becoming a necessity for business survival.
Corporations that subscribe to WAN communications services from major carriers have the ability to control determinate bandwidth, which allows corporations to implement network telephony with a PSTN-like quality of service that does not exist in Internet telephony implementations.
This sets the stage for network tele-phony to be first adopted in the corporate world. The enabling factors include the managed WAN bandwidth, while the driving forces are the hard-dollar cost savings and soft-dollar productivity gains.
Internet service providers (ISPs) are in a unique position to provide network telephony offerings to both individual users as well as enhanced services to business and corporate users. ISPs already are in the service provider business with ever-increasing number of both individual and business subscribers. Those ISPs that adopt network telephony are being referred to today as Internet telephony service providers (ITSPs). ITSPs can provide a variety of network telephony services that are user-oriented services, business-oriented services or a combination of the two.
Companies such as NETCOM On-Line Communication Services Inc., San Jose, Calif.; PSINet Inc., Herndon, Va.; and Qwest Communications International Inc., Denver; and others are currently offering some form of network telephony. Since these large ISP/ITSPs own or contract their points of presence (POPs) and network backbones, the quality of voice over their networks is controllable and the billing issues and rate settlement are straightforward issues.
Business Communications Services
The need for customer premises equipment (CPE)-based network telephony gateways becomes driven by the corporate calling needs and patterns. Typically, a corporation leases on-net voice services from a major telco carrier to provide less expensive calling rates between corporate offices. This requires an additional T1 line from the corporate office to the carrier POP for the voice channels. Since the company also has local-loop leased lines connected to its contracted ISP, voice can be carried, as data, over the ISP connection at a substantially lower cost than that offered by the telco. Due to this data network connection, the network telephony gateway must be CPE-based and located at the customer site.
By providing CPE-based network telephony gateways, the ITSP can provide many of the enhanced service offerings by integrating with the existing PBX and network directory. The ITSP can provide and manage not only a data virtual private network (VPN) for its business subscribers, but also the voice VPN as well.
Network telephony has emerged as one of the most important and fast-growth industries of our time. It provides the capability of lowering the cost of call minutes, network infrastructures and network management, as well as the immense capability to provide an entire new range of communications services that can be integrated with the new class of telecom servers and collaborative computing applications.
The combination of reduced costs and new services will result in an overall increase in call-minute usage that further will spur the growth of network telephony as the preferred communications media of the future. Those ITSPs that embrace it will see revenues increase and those that do not will almost surely see declines. These trends will be first noticed in the international and corporate communications arenas through network service providers and VPNs with personal communications services soon to follow from telco carriers and ITSPs.
Gary L. Andresen is vice president of marketing of StarVox Inc., San Jose, Calif. He can be reached at (408) 383-9900.
