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Why Use SIP for IP Communications?
What the Session Initiation Protocol can Mean for Your Business


Any business thinking about implementing IP telephony should ask one question before anything else: Why use a network architecture based on the Session Initiation Protocol (SIP) to support IP communications? Businesses should at least take a look at the SIP open communications standard and do their homework on it.

Objectively, it isnt that an organizations IP telephony initiatives are destined to fail if they dont incorporate a SIP-based network for any required migration up-front and for long-term use thereafter. However, leaving SIP out of the mix can definitely diminish the level of IP success, as can an IP PBX phone system that stems from traditional proprietary PBX hardware architecture not made for SIP-driven IP communications.

Heres a look at why many proprietary IP PBX solutions dont even accommodate SIP, some of the pitfalls of not using it, and why the SIP standard really is your businesss best choice for supporting Internet Protocol communications.

Hardware Simply Isnt Designed for SIP

One reason most vendors in proprietary circles have yet to adopt SIP for their IP PBX hardware offerings is the SIP standard itself. In short, SIP is software-based, open and lightweight, and is designed to direct IP telephony calls to application servers on a data network the same way e-mails, Web chats, and other media are. Moreover, SIPs inherent simplicity makes application interoperability much easier than do hardware systems and older voice protocols, such as ISDN which are well-known for system compatibility problems, and which is why IP technologies have been developed primarily as software applications.

According to a recent Gartner report, The IP PBX Is A Potential Architectural Dead End (April 2005), many current IP PBX hardware products rely on centralized proprietary IP architecture to replicate the digital model their PBX forefathers used a decade ago. Go back further in time, and the 90s digital model actually evolved from the proprietary PBX architecture model first introduced in the 1950s. With such a lineage of legacy thinking behind proprietary IP PBXs, its just as the analysts at Gartner so succinctly stated: proprietary approaches to IP communications fail to leverage emerging Internet telephony standards, and will not support a distributed and open telephony architecture.

The result? Choose proprietary IP PBX hardware that cant accommodate open standards such as SIP, and your choice of voice applications is limited to those offered solely by the proprietary vendor or an approved affiliated vendor effectively locking your organization in to that vendors IP solutions. Same thing if your business wants to integrate third-party communications applications, which the same vendor is only more than happy to do through a high-priced computer telephony integration (CTI) interface. Besides, in an industry that generates billions of dollars annually from hardware sales, theres little room for cost-effective software and future-proof open standards.

Given the software nature of SIP, then, the majority of new IP PBX systems now on the market are designed as standards-based software applications to fit SIP networks for IP telephony. Being software-oriented also aligns many of these IP PBX solutions more closely with the SIP model to support cost-reducing third-party IP phones and soft phones as well as mobile devices, desktop PCs, and traditional analog telephones.

No Business Value

Say your business takes the hardware path to IP telephony anyway and implements an antiquated proprietary IP PBX and closed hardware architecture that doesnt utilize the SIP communications standard. Along with your IP PBX not connecting to other voice and data systems, it wont let you add business value to your overall communications solution beyond what a traditional PBX would.

Particularly in this age of IP PBX software, one of the beauties of SIP is the ability it gives your organization to integrate an IP PBX application server alongside data servers on a single network and to administer them all from that same converged network environment. Dont use SIP architecture, however, and your business is left staring at the Great Voice and Data Divide from disjointed phone equipment and data systems and their equally disjointed administration.

Worse still, if your enterprise maintains multiple offices, bypassing SIP inhibits your ability to standardize technology across sites for users, desktops, and customer features, which can lead to business process disparity from site to site, business continuity management issues, and inconsistent service levels for customers, not to mention the expense of maintaining lines between remote office locations.

What SIP Brings to the Table

A SIP-based architecture for IP telephony offers voice and data business communications functionality that is, in a word, practical. Imagine using a single IP PBX software server and SIP-supported network to drive a mix of voice applications, such as live conferencing, instant messaging, and other media. Also imagine pre-integrating business applications that embed open standards for interactions generated from those same applications.

For instance, use a SIP network to implement the IP telephony software from Interactive Intelligence or the Microsoft-based IP PBX software from Interactive Intelligence subsidiary Vonexus, and you can easily:

Pre-integrate Microsoft Windows Server System products, like Exchange Server, SQL Server, and Live Communications Server all out of the box.

Implement a server for the Microsoft Business Solutions applications your business uses most and get Interactive Intelligence/Vonexus innovations like IVR data access, integrated CTI screen pop, and embedded Client call controls for Microsoft CRM, Great Plains, and other applications from Microsoft Business Solutions suite.

The open architecture and application interoperability your business gets with SIP and IP telephony also lets you:

Reduce equipment costs. Easily replace up to 10 hardware boxes with bundled software applications for features like ACD, IVR, fax, voicemail, and choose from third-party IP phone sets that often sell for less than $100 per device to save over proprietary ones that often cost four times as much or more.

Streamline system administration. Integrate an IP PBX application with systems for conferencing, unified messaging, and other media on the same SIP network, and eliminate multiple admin interfaces as well as the need for separate IT voice teams and data teams. Using SIP with a standard operating system and troubleshooting tools also simplifies desktop and endpoint management enterprise-wide.

Reduce costs for lines. Realize tangible savings from SIP-based carriers that use bandwidth for voice communications, rather than more expensive traditional TDM lines. Toll bypass cost reductions also lend to long-distance savings.

More so for a mobile workforce, SIP-based IP communications allow remote and mobile employees to stay connected full-time to your enterprise and customers alike. Workers can hot-desk from virtually any office location, access the corporate communications system and mission-critical data at any time from wherever they are, and utilize multiple devices such as laptops, cell phones, and hand-held devices based on their mobile login choice. SIP networks for IP even let your multi-site business route calls to the specific location from which a mobile user logs in.

SIP for Your Bottom Line

Recapping the question your business should ask about why SIP is the best choice for supporting IP telephony, its safe to say the answer is a multi-benefit response that goes something like this:

Virtual company communications applications.

User and endpoint applications based on user type.

Increased workforce accessibility and more efficient use of employee time.

Faster, more consistent service for customers.

Lower investment and maintenance costs for software over hardware.

Easier administration from a single voice and data network that fits an organizations Microsoft strategy.

Processing per office location and or department based on specific application requirements.

No more business continuity concerns.

And that all-important future-proof technology approach to SIP-based IP telephony applications that proprietary IP PBX hardware simply cant provide.

Peggy Gritt is Senior Director, Product Marketing for Interactive Intelligence Inc., a global developer of software for contact centers and the enterprise since 1994. Interactive Intelligence integrated out-of-the-box IP functionality into its lineup of business communications software solutions in 2002, and along with its Vonexus subsidiary is a leader in the SIP movement for VoIP. Contact Interactive Intelligence at 317.872.3000 voice and fax, or visit for more on the companys complete suite of IP communications solutions.

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