| ID Number: AV-20-4462 |
Creating an Enterprise VoIP and IP-Telephony End-to-End View
25 July 2003 Bern Elliot Enterprise architects and managers must explicitly define the end-to-end functional layers of their enterprise voice over IP infrastructure and IP-telephony application architecture.
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Business Value Drives VoIP and IP Telephony Enterprise architects and managers must explicitly define the end-to-end functional layers of their enterprise voice over IP (VoIP) infrastructure and IP-telephony application architecture; this will clarify the tasks of integration and cost justification. Figure 1 shows the five major functional layers in an enterprise deployment. The lower layers provide the enabling network and VoIP infrastructure, while the upper layers show the IP-telephony applications and communications-enabled business processes. Viewing the enterprise in terms of these functional layers clarifies the technical aspects because the products, vendors and replacement cycle for each layer differ. The project management tasks and business justification are clarified because the departments and stakeholders involved in implementing each layer are usually different. Functional layering allows the cost and management for any single layer to be placed in the broader context of business value. Each of the papers in this Spotlight provides insight on the business issues, technology and vendors in these layers. A context for the Spotlight is provided in an article by Bern Elliot, which provides a framework for understanding VoIP and IP telephony and additional information regarding this five-layer model. Figure 1 VoIP and IP-Telephony Functional Layers

Source: Gartner Research (July 2003) VoIP-Capable Networks This layer of functionality allows WAN connectivity between locations or companies and is offered through asynchronous transfer mode (ATM), frame relay or, increasingly, through Multiprotocol Label Switching (MPLS) and virtual private networks (VPNs). The article by Jay Pultz provides an understanding and evaluation of carrier VoIP services. The article by Katja Ruud provides a perspective on how carriers in Europe are approaching the VoIP access market and how enterprises should evaluate these services. VoIP-Enabling Infrastructure The components at this level of functionality provide enterprise-specific infrastructure to enable and secure voice traffic over enterprise LANs. This layer does not provide the telephony itself. The research by David Neil provides analysis of how to ensure that the enterprise VoIP network is reliable and capable. The article by John Girard and Andy Rolfe provides critical best-practice guidelines regarding the security of the VoIP environment. IP Telephony This is the functional area that provides basic telephony and voice-switching functionality, including traffic management, call setup and tear-down, call control, and reporting. Two articles by Richard Costello provide background on Session Initiation Protocol (SIP). In the first, Costello outlines the central role that the SIP will play. In the second article, he provides a perspective on SIP softphone product offerings. Advanced IP-Telephony Applications This level introduces the value-added telephony applications that build on the base IP-telephony/IP-PBX capabilities. The more common IP-telephony applications are contact center functions, unified communications and conferencing. The Research Note by Drew Kraus advises where, when and why contact centers will move to VoIP. The article by Terry Wright provides a perspective on the criteria enterprises use when selecting IP contact center solutions. Business Applications and Value of IP Telephony Broader IP-telephony initiatives often involve changes to those business processes that will allow this technology to be properly leveraged. These changes can include those rules, roles, procedures and structures that are related to the communications and exchange among people as well as between the environment and people. The specific changes differ between enterprises, industries and deployments. The article by Steve Blood describes the state of using VoIP for remote workers. The article by Bob Hafner defines a model for understanding how enterprises' IP-telephony applications will evolve as the technology gets diffused and adopted in the enterprise over time. Together, the research in this Spotlight provides comprehensive views and models that will allow enterprise managers to successfully plan and deploy VoIP and IP telephony in their enterprises. Features "Business Value Drives VoIP and IP-Telephony Layering" — Vendors, stakeholders, technology and evolution rates deliver complete business value. By Bernard Elliot "Voice Over IP: WAN Considerations" — Managed, enhanced WANs are for mainstream voice communications. By Jay Pultz "How to Assess the Case for Voice Over IP Services" — Organizations should consider the savings, features and call quality that these services bring, rather than focusing on the technology. By Katja Ruud "Network Assessments for VoIP Help Improve Service" — Enterprises must distinguish between traditional voice services and VoIP. By David Neil "VoIP Security Behind the Firewall" — VPNs can be used where appropriate. By John Girard and Andy Rolf "SIP Will Make Significant Inroads by the End of 2006" — Session Initiation Protocol will likely be preferred over VoIP. By Richard Costello "A Product Survey of SIP 'Softphones' " — Full multiplatform interoperability with softphones seems unlikely. By Richard Costello "IP Contact Center Considerations and Timelines" — Enterprises must select the IP contact center that meets their road map. By Drew Kraus "Vendors Must Exploit IP to Achieve Contact Center Sales" — Vendors must identify how IP technology migration relates to scalability, performance, ease of integration and management. By Terry Wright "Don't Rely on Voice Over Internet for Teleworkers" — Voice over Internet will not replace the public switched telephone network for voice calls. By Stephen Blood "IP Telephony Can Revolutionize Business Communications" — Enterprises must rethink how they used voice applications. By Bob Hafner

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