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SIPping into Something More Comfortable




VoIP is a pretty familiar term these days, thanks to effective mass market campaigns by service providers and virtually everyone from Time magazine to The Wall Street Journal weighing in with an opinion on its future. But your customers may be wondering about how additional data applications tie in with the cheap voice minutes VoIP offers. The answer relates to SIP, an open-standards protocol for getting devices and services to talk to each other.

SIP, which stands for Session Initiation Protocol, is a set of standards-based signaling protocols developed by the Internet Engineering Task Force (IETF), the same group that brought us HTTP and TCP/IP, building blocks of the Internet. Being standardized, SIP allows for security development and standard APIs for developers, meaning any number of Internet conferencing, telephony, presence, events notification and instant messaging applications can be created and enabled. In other words, SIP enables real-time multimedia communication over IP.

Beyond Basic VoIP

SIP, already well-accepted in many regions of the world, will have an initial impact on the marketplace by making VoIP more than a cheaper way to place a telephone call.

VoIP users care about the overall experience, not the technology employed to provision the service, says Agatha Poon of the Yankee Group. From making a VoIP call using a computer or regular phone to placing a VoIP call using a simple point-and-click interface, the call control is extended from the network to the desktop level with SIP, she notes. For the first time, callers are in control of their calling experiences by using an expandable list of calling functions, such as priority calling, simultaneous ring and voice-to-text messaging.

The evolution of IP not only inspires wide-ranging development of Internet applications, it changes the way service providers develop and market services, says Poon. Although carriers first introduced VoIP as a cost-effective alternative to conventional long-distance services, the toll bypass opportunity of VoIP has become less pronounced [in certain regions], with a few exceptions in markets where basic voice services remain hefty.

SIP-enabled VoIP and multimedia services represent a way to avoid commoditization and to gain new revenue streams.

What Else Does SIP Do For Me?

In the traditional world, every service has its own protocols. TDM voice uses a different set than instant messaging, for example. Vendors have developed proprietary protocols for certain equipment and services, leading to further complexity for the CIO in any business. SIP eliminates that chaos by becoming the one protocol that supports all IP-based multimedia services, regardless of user, device or vendor.

Avaya Inc. notes in a white paper that SIP will be instrumental in the evolution toward a converged IP communication architecture. So, picture a multivendor environment with multiple applications across a wide range of industry sectors, where communications will be driven by ubiquitous IP network connectivity and SIP.

What does it mean for agents? For one, this scenario translates into a booming marketplace for selling high-value services to businesses for big commissions. Add-ons to existing VoIP packages such as customer relationship management applications, multimedia conferencing and location-based services become simple with SIP. And VoIP may be an even easier sell once it comes with the promise of hassle-free data service add-ons for enhanced productivity.

Businesses will become more comfortable in the world of advanced services without the fear of vendor-lock, being tied to an expensive set of proprietary equipment. A SIP server carries virtually no danger of becoming obsolete.

Agents and VARs also can capitalize on the sale of hardware to businesses for the purpose of enabling SIP communications. Companies such as Avaya Inc., BayPackets Inc., Cisco Systems Inc., Ubiquity Software Corp. and others use partners to deploy their offerings to the marketplace.

How Does it Work?

The thing to understand about SIP is that it is peer-to-peer. Imagine devices and advanced services communicating in much the same way people e-mail each other: no major network intelligence or configuration necessary.

According to a white paper authored by Jonathan Cumming, director of marketing for protocol software at Data Connection Ltd., SIPs view of the network matches that used in the Internet: intelligent devices communicate directly with each other over a simple transport infrastructure. This contrasts with the traditional telephone network, where transport between dumb endpoints is provided through an intelligent network core that is an active party in any conversation.

Users in a SIP framework are identified by Universal Resource Identifiers (URI), similar to e-mail addresses. The addresses are mapped to contacts, which are devices or services where the user may be reached: IP phones, desktop multimedia clients, instant message accounts, e-mail accounts and so on.

The SIP framework routes requests for peer-to-peer sessions between URIs and its contacts, using the preferences, presence and location of the user. The protocol also provides mechanisms to specify the type of session requested: a phone call, video conference, chat and so forth. So, one user can communicate from his device and service of choice say, video over a 3G wireless handset to another person using his or her preferred communications method say, video chat on the desktop at the office.

According to Cisco, a SIP-based network is made up of several components:

  • SIP User Agent any network endpoint that can originate or terminate a SIP session. This might include a SIP-enabled telephone, a SIP PC client (softphone) or a SIP-enabled gateway.
  • SIP Proxy Server a call-control device that provides many services such as routing of SIP messages between SIP user agents.
  • SIP Redirect Server a call-control device that provides routing information to user agents when requested, giving the user agent an alternate URI or destination user agent server.
  • SIP Registrar Server a device that stores the logical location of user agents within that domain or sub-domain. A SIP registrar server stores these locations and dynamically updates its data.

It may seem like a lot to take in, but learning about SIP will pay off for channel partners: Our interviews with a dozen of service providers and vendors show Session Initiation Protocol technology is in the spotlight. SIP, an application layer signaling protocol, is being considered as a tool to build a reliable foundation for VoIP, says the Yankee Groups Poon. Its ability to establish, manage and terminate interactive multimedia communication sessions over IP networks is appealing to providers of all kinds. Equipment vendors are bullish on the potential for SIP-enabled products. Their enthusiasm in embracing the technology should bring a fresh perspective in both the carrier and enterprise markets.


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