go directly to SIP Conferencing Call Flow
Setting The Course For
Profitability And Growth
BY ERIC BURGER
While the telecom seas remain rough, there is a growing consensus about
the proper course for the telecom industry to take as it attempts to
navigate towards the safer waters of sustained profitability and growth.
The course is simple: Develop and deploy new, differentiating enhanced
IP services that can drive up both subscriber demand and service provider
This sounds simple, but questions still remain. What are the tools
needed to drive these new services? How are these new tools implemented?
The answers lie with SIP and a SIP-based services infrastructure.
Session Initiation Protocol, or SIP, has emerged as the control
protocol of choice for U.S. and international service providers that are
deploying converged services and IP infrastructures. SIP is a simple and
flexible call control and signaling protocol that enables the rapid and
efficient development and deployment of innovative third-party converged
applications in service provider networks.
Developed under the auspices of the IETF, SIP facilitates the setting
up, changing, and terminating of multimedia sessions across diverse
Three key attributes make SIP the new gold standard for enhanced
ï¿½ SIP is ubiquitous. Because SIP is based on established, open
protocols (derived primarily from HTTP), there are a large body of open
implementations, ensuring a vibrant, competitive set of offerings and
ongoing innovation. This openness enables the real time integration of
diverse voice, video, and data content (Web, e-mail, etc.) into
applications, broadening application features and providing a richer end
ï¿½ SIP is simple. It is a text-based protocol thatï¿½s easy for
developers to understand and use. SIP leverages proven Web development and
deployment paradigms. It substantially widens the pool of development
talent and available tools. Most importantly, this paradigm makes new
service deployment faster, cheaper, and easier to operate.
ï¿½ SIP is flexible. SIP-based architectures are distributed, much like
PC architectures of the IT world. Just as the PC supplanted centralized
mainframes, SIP puts the intelligence for call control and features on
distributed devices. Such devices include SIP proxies and SIP Application
Servers in the network and Media Gateway Controllers (MGCs) and SIP phones
or soft phones (PCs) at the edge of the network. This contrasts to the
centralized model of the TDM world where processing and control
intelligence reside on large phone switches or server in the network core.
SIP SERVICES ï¿½ MAKING THE CONNECTIONS
SIP works with existing Internet protocols, enabling endpoints to
discover one another via network hosts, and agree to share sessions. This
application-layer control protocol lets users establish, modify, and
terminate multimedia sessions such as conferencing, Internet telephony
calls, and instant messaging sessions Overall, SIP supports five functions
for establishing and terminating multimedia communications:
ï¿½ User location -- Identifying end systems to be used for
ï¿½ User availability -- Determining the called end userï¿½s
willingness to engage in a call.
ï¿½ User capabilities -- Specifying the media and media parameters to
ï¿½ Session setup -- Establishing session parameters for both the
calling and called parties.
ï¿½ Session management -- Modifying session parameters, invoking
services and terminating the session.
HOW IT WORKS: SIP CONFERENCING
SIP conferencing enables the easy integration of new multimedia
features and greater end user flexibility and control. What does this mean
to the consumer? No longer do conference calls require users to call into
a centralized bridge at a set time with no guarantee of 100 percent
attendance. Utilizing presence-based technology and a convenient Web
interface, a blast to your IM buddy list or e-mail contact list enables a
conference call to be arranged in seconds. Callers will no longer be
subjected to the painful sounds of elevator music nor have to engage in
the mindless pre-conference chit chat while waiting for a conference call
SIP Conferencing means calls commence in seconds with 100 percent
attendance due to presence. Callers can select their own choice of musical
accompaniment if they want, by piping in a popular MP3 tune from a Web
site and playing it into the call. For business conference calls, new
enhanced features such as peer-to-peer file sharing enables conference
participants to collaborate in real-time on joint projects such as sales
presentations or architectural drawings, all with the click of a mouse.
The ï¿½hurry up and waitï¿½ of TDM-based conferencing is transformed into
a real-time, interactive communications experience that is not only more
compelling and flexible for the user, but a good deal cheaper.
From the service provider perspective, enhanced SIP conferencing is a
far easier application to develop and deploy. It requires an IP-based
services infrastructure consisting of a conferencing application server
and a media server platform.
ï¿½ The conferencing application server holds the logic for the
application. Its functions include establishing the conference, providing
participants with the information necessary to join the conference and all
aspects of conference control and management. The conferencing application
server uses SIP to control the media server and to manage and direct media
sessions during the conference call.
ï¿½ The media server works on behalf of the conferencing application
server and receives directions via SIP from the application server. The
media server mixes media sessions, delivers audio streams, plays and
records media to and from the conference and supports all the IVR
functions required for the conference on behalf of the application server.
The media server also has the capability to perform transcoding functions
for multimedia terminals.
For the service provider, the deployment and management of a SIP
conferencing solution gives them more flexibility and efficiency and most
importantly more profit potential.
Although vendors and service providers still must weather the telecom
storm, the course has been set. SIP and SIP services offer unprecedented
opportunity. SIPï¿½s ubiquity, simplicity, and flexibility make it a
compelling technology for navigating your way to the calm and safe waters
of profitability and growth.
Eric Burger is CTO and co-founder of SnowShore Networks. He is a key
contributor serving on numerous working groups for SIP and VoiceXML for
the W3C, IETF and 3GPP. Burger co-authored the SIP application media
server interface requirements draft for the IETF and has guided the
development of VoiceXML for the W3C. For more information, visit the
companyï¿½s Web site at www.snowshore.com.
PLEASE VISIT THE SIP CENTER:
The SIP Center is a portal for the commercial development of the
Session Initiation Protocol. Serving both the SIP community and the wider
industry, the SIP Center offers comprehensive technical and market
resources as well as an environment for the testing of SIP
implementations. Visit The SIP Center online at www.sipcenter.com.
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