SIP is sneaking into the enterprise

Despite all the hype starting to surround SIP (session initiation protocol), implementation among readers polled in a telephony survey done by InfoWorld, a US sibling publication of Computerworld, appears surprisingly small.

Despite all the hype starting to surround SIP (session initiation protocol), implementation among readers polled in a telephony survey done by InfoWorld, a US sibling publication of Computerworld, appears surprisingly small.

Only 5% of respondents say they are using SIP, and even fewer, 4%, plan to continue using it in 12 months; just 11% said they'll start using SIP in the next year.

SIP is an industry standard protocol for setting up multimedia telephony sessions, usually over the internet or other IP network. Headquartered in Stockholm, Sweden, the SIP Forum is coordinating the development of the standard, based on lessons learned from HTTP. Like its precursor, SIP is a text-based protocol that works well with most network infrastructure. Hundreds of vendors are producing or are on the verge of releasing products that use SIP.

With so few survey respondents reporting plans for SIP, is it possible that the IT managers who buy telephony products for their companies don't know they're using SIP? SIP seems to be slipping into their operations unnoticed and unknown.

Take a look at the other technologies that respondents are using. Twice as many plan to use 3G phones next year compared with those who plan to use SIP. But because communications between 3G phone switches are broadcast entirely through SIP, in reality, that 22% of future 3G users will be using SIP whether they know it or not. Likewise, H.323 videoconferencing systems and GPRS (general packet radio services) communications are very likely to be SIP-enabled, even if that fact is not listed in the spec sheet.

According to Anne Coulombe, a member of the SIP Forum and the head of SIP-based solutions for Mitel Knowledge, a broadband R&D company in Ottawa, the real issue may be that IT executives are concerned only with the applications in which SIP is used.

Coulombe compares the SIP standard to SMTP. Although most email systems use SMTP in some fashion, she suggests that if asked a similar question about the email standard, the response would be similar; almost no one considers the standard when thinking about email. Coulombe explains that SIP is the protocol that allows a company's diverse telephony solutions to work together: "It's the glue inside like SMTP is the glue for email."

Because SIP works so deeply within the background of a telephony session, it's rarely obvious that it's being used. This means that you can make a call from a 3G phone, use some of the 3G multimedia features, and never realise that the means for setting up the calls and initiating the sessions used SIP.

Interest in SIP is growing at all levels. According to Coulombe, more than 120 vendors attended a recent SIP summit, including 35 just entering the SIP market. Where is the growth in SIP taking place? Partly, she says, it's among smaller companies that do not already have a huge investment in telecom equipment. At larger companies, SIP is going into the edges of their communications infrastructure, where it complements existing PBX equipment, which for most companies isn't ready to replace just yet.

Still, SIP support will go into place. Multimedia applications are growing at many companies, making SIP a necessity. More importantly, SIP is the standard telephony protocol used by Microsoft's Windows XP and .Net operating systems. One way or another, companies will be moving to SIP, whether IT managers know they are or whether they even intend to.

SIP is well on its way to being broadly used and widely supported, but as with some other standards, few users know they're using it. Adding to the confusion are other standards and protocols that many consider exclusive to SIP. SIP is becoming important enough to create demand for it in Class 5 circuit switches, and it's showing up in force at the edge of the telephony network in switches, voice-mail gateways, and handsets. And, of course, SIP is already part of 3G mobile telephone networks globally.

SIP is still in its infancy. The standard was finalised just a few months ago, and only now are products starting to appear in large quantities. One thing is sure: The use of SIP will grow rapidly in your telephony infrastructure. For the most part, this probably won't matter to you, but there are places where it will. For example, your firewalls will need to be told about SIP if you use it, and it needs to communicate outside the network. If you use load balancing that performs packet inspection, it will need to know about SIP as well.

How will you know if you are using SIP? Most new telephony products, including videoconferencing systems and PBXes, especially those using multimedia, will incorporate it. As these products grow, so will your use of SIP.

One way or another, it'll probably show up on your network, so when you plan for changes, also plan for SIP.

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