Executive Overview

The vision that Avaya has for converged voice and data communications is to create a network environment that supports maximum enterprise efficiency. Session Initiation Protocol (SIP) is a key technology for this evolution towards a converged communication architecture. SIP as an enabler of converged communication applications has been able to gain industry-wide acceptance by placing control of the communication across distributed networked entities and by providing a means of integration at various levels in the protocol stack. Such integration is now possible in a multi-vendor environment with multiple applications across a wide range of industry sectors. Converged communications that is driven by ubiquitous IP network connectivity defines the next stage of evolution in enterprise communications.

SIP is an application layer, peer-to-peer communication protocol that facilitates openness, simplicity, flexibility, and reuse in an "All IP" Architecture. This section offers a look at how Avaya views SIP in enterprise evolution. It also describes SIP technology, elaborates on the role of SIP in realizing converged communications, and describes details of the SIP protocol and associated technologies.

Evolution to Converged Communication

Enterprises will evolve portions of their infrastructures from one phase to the next according to their business needs and will often be in more than one of these phases at the same time. In the traditional phase, enterprises have separate infrastructures for voice and data networks, with time division multiplexing (TDM) for voice and IP for data. In the converged networks phase, enterprises build out their IP networks to leverage a common infrastructure for both voice and data. This enhances the IP network to meet enterprise-class criteria: improving quality of service (QoS) and increasing the reliability of real-time, mission-critical business and communication applications. As enterprises become more distributed and business performance needs dictate enhanced user capabilities, converged communications applications will be deployed. The essence of converged communications is modularity: network components and applications that can be used over a wide variety of systems.

As solutions become more modular, their services can be deployed in a greater number of configurations and more easily integrated into multi-vendor environments, which can lead to increased network flexibility and cost efficiency. Avaya is taking the lead in modularization of its software and systems into an open communication architecture to help organizations smoothly transition to converged communications for a more adaptive enterprise.

COMMUNICATIONS AT THE HEART OF BUSINESS

Evolution to Converged Communications

As enterprises become more virtualized and the needs for ubiquitous end user capabilities become a critical business imperative, enterprises will begin to evolve to a Converged Communications phase. In order to leverage their existing investments in various technologies, businesses will naturally evolve parts of their infrastructure from one phase to the next. As such, they will often discover themselves in more than one of these phases at the same time. For example, the majority of enterprises today are transitioning between Traditional and Converged Networks, with a few visionary enterprises starting to transition to Converged Communications. Due to this gradual migration, it is essential that an enterprise's solutions are evolutionary enough to accommodate existing infrastructures and investments, while at the same time provide a new foundation for deployment of new applications and services.

Avaya Converged Communication Evolution with SIP

Session Initiation Protocol (SIP) is a simple protocol that facilitates peer-to-peer communication sessions. Users (or, in general, any addressable entities) in a SIP framework are identified by Universal Resource Identifiers (URI). Each such Internet-style address (for example, sip: johndoe@avaya.com) maps into one or more Contacts, each of which typically represents a device or service at which the corresponding user may be reached. Examples are phones, desktop multimedia clients, instant message accounts, email accounts and so on. The SIP framework is responsible for routing a request for a peer-to- peer session addressed to a given URL to one or more appropriate contacts for that URL. The framework may utilize information about the preferences, presence and location of the user identified by the URL, to determine the most appropriate contacts. The protocol also provides mechanisms to specify the type of session that is requested as well as means to change session parameters. In current paradigms, solutions are intricately tied; for example, users call each other using a set of voice application related protocols, and users send Instant Messages (IM) using another set of protocols. The situation is further complicated when multiple vendors employ proprietary protocols (or protocol extensions). In addition to the complexity of Enterprise CIO operations forcing communication into specific silos, this reduces end user productivity.

A SIP-based solution changes that paradigm by allowing users to indicate the fact that they would like to communicate to another user, but using a user's preferred mode. SIP-enabled Avaya converged communication makes that easier for enterprises. " The Avaya Converged Communication Solution is geared towards helping Enterprise CIOs to benefit from the impact of SIP based converged communication in the broad areas of Voice over IP (VoIP), Unified Communication, Customer Relationship Management (CRM) solutions. It lays out the foundation for migrating to an enterprise SIP network. Though SIP is gaining popularity within the communication industry as a "telephony protocol," in reality, SIP is applied to a wide variety of communication sessions such as voice, video, instant messaging, presence, conferencing and real-time collaboration. SIP has become the industry-wide standard mechanism to achieve real-time interactive converged communication services. SIP provides a practical method of service integration across multiple networks -- such as Enterprise/Service provider network and TDM/IP network -- using multiple modes in a media independent way. In this way, SIP changes the focus of communication from the modality of the communication to a user level representation of a session. SIP is also a vital component of next-generation enterprise and carrier wireless networks. With these properties, SIP is an important enabler of converged communications, where the emphasis is on ubiquitous end user capabilities and end user control. SIP is to converged communication what HTTP is to information exchange for the World Wide Web (WWW) -- it makes the communication infrastructure transparent to the end users and enables ready access to many modes of communication. Through its use of the URI, SIP enables a communication request to be handled in the same manner as an HTTP request, creating a natural solution for integrating communication services and enterprise applications.