SIP is the future of telecommunications

SIP is the future of telecommunications

Summary: As was clear from last week's ITEXPO in Los Angeles, SIP is shaping up to be the standard replacement protocol for the traditional TDM / SS7 network. SIP trunking starts to make it possible to offer an end-to-end digital communications solution that can call any number in the world...without a traditional phone line anywhere in your organization.

SHARE:
24

The 18th Internet Telephony Conference & Expo (ITEXPO) came to Los Angeles last week, and being the opportunistic sort, I decided to get myself on the press list. That's one of the advantages of writing for ZDNet. Conference organizers will often let you attend their creation for free in hopes that you might write something about the products on display therein.

I'm not, however, one of those writers who likes to post a play-by-play of the happenings at this or that conference. I prefer to attend the entire conference, visiting all the classes and study groups which, to my mind, serve as the highlight of such things, only to figure out afterwards what new thing I have learned from the whole process.

I did note that this was the 18th ITEXPO...which means that there were companies thinking about a future where communication was entirely mediated by Internet-related protocols as far back as 1990. In 1990, the notion that a web of connections mostly linking academic institutions might serve as the foundation underpinning something as critical as voice communications must have seemed, to some, like so much technophile hyperventilation. Clearly, however, the Internet has been more than a little bit succesful. Furthermore, protocols designed to run over Internet connections seem to be reaching a tipping point with respect to their adoption by telecommunications companies. I'm not just saying that because I am still responding to the "reality distortion field" caused by the strange chemicals conference organizers insert into their continental breakfasts. Looking back, most of my career seems to have been spent working for one telecommunications company or another (though video-related work seems to have occupied most of the rest).

One thing that has already been rolling along for quite some time, but has become extremely apparent given recent developments in the industry, is that Session Initiation Protocol (SIP) isn't just a protocol that is "popular" in Voice over IP (VOIP) environments. It is, for all intents and purposes, THE VOIP protocol, at least among traditional telecommunications providers. It is the protocol that networks choose when they want to IP-enable their largely SS7 environments (SS7 is the signaling protocol used in the global circuit-switched network used to communicate within and between almost every telecommunications company in existence). SIP plays a central role in the IP Multimedia Subsystem (IMS), a family of protocols which is supposed to define the architecture of next-generation mobile networks capable of streaming various kinds of text, voice and video data to mobile phone subscribers even as they roam between networks.

Though the people at the conference were clearly fans of an IP, and SIP-based, future, nobody believed that SS7 was going to go away tomorrow. The existing investment in SS7 is massive, and telecommunications companies aren't going to replace overnight a technology into which they have sunk many billions of dollars in investment and which reliably serves the voice communications needs of the entire world. However, as we move beyond a network mostly built to cater to the needs of voice, SIP is simply a more flexible alternative.

Session Initiation Protocol (SIP) is, at least syntactically, a lot like HTTP. It confines itself to simple negotiation of data streams between endpoints, and doesn't impose any kind of rules as to the nature of those data streams (though streams of data are usually packaged inside RTP, another publicly-ratified protocol). SIP, in other words, can be used to negotiate a voice connection, as well as exchnage text message of varying sizes and complexities, exchange presence information, and exchange any kind of data the nature of which can be described via MIME headers and the protocol details for which can be described via Session Description Protocol (SDP, which is exchanged as part of SIP negotiation). SS7, in theory, can be used to negotiate multiple kinds of data streams as well, but the history of the development of the traditional phone network means that most endpoints can, at most, handle basic audio encoded according to G.711 rules (a limitations of the vertically-integrated switch hardware that was the norm for most of telephony product history). Further, though SS7 is a simple signaling protocol as well, it doesn't have the level of expressiveness and flexibility as a text-based protocol like HTTP or SIP.

HTTP has proven to be one of the most popular media exchange negotiation protocols in existence. SIP borrows many of those semantics, and makes media exchange negotiation more flexible still.

But if I don't dive deep into a blow-by-blow description of the intricate details of the SIP protocol Right Now, knowledgeable readers will pillory me for being excessively vague. So, I will stop here, and note that you can find stacks of documentation about the SIP protocol on the Internet and / or books published by any number of publishers. That's the magic of a public and officially-ratified protocol. There's no real mystery about its details.

Of particular note at this conference, however, was the emphasis on the concept of "SIP trunking." Traditional TDM trunking is often via a T-1 / ISDN PRI connection. T1 connections are ridiculously expensive ($500 / month is not uncommon, and it used to be much more), particularly when you consider that they only provide a maximum bitrate of 1.544 mbps over the 24 unique voice / data channels a T1 provides, each of which runs at 64 kbps (the European equivalent, E1, gives you only a bit more, at 2.048, with 30 voice channels). Given the bandwidth limitations of TDM trunk connections, few businesses would use a T1 or E1 link for anything but their voice communications.

This makes T1 connections an extra expenditure on top of digital data links. Further, there is a translation step for many businesses using modern business telephony products, many of which use SIP as a means to communicate between telephony endpoints within the business. A far cheaper and flexible way to achieve your office communications needs would be to dispense with that TDM connection entirely and use that data channel as conduit for all of your communications.

SIP trunking allows you to do that. By paying for a SIP trunk connection, you don't need to have any kind of phone line hooked into your office. You just pay for a SIP connection from the SIP trunk provider of your choice, and your SIP-compliant software has all the telephony connectivity it needs.

One of the advantages of this model is that you aren't tied to just a number in your local area or country. Given that SIP abstracts away the concept of where you are, it is easy to have numbers in multiple countries that feed back into your central office. This gives small companies the ability to seem like much larger companies, something from which my company, which is extremely small, could certainly benefit, but from which even home users can benefit. SIP trunking also allows you to escape reliance on the owner of the phone or cable lines that run into your home for voice service, moving beyond cable-based VOIP services, and even consumer services like Vonage, to allow a web of VOIP providers to compete for your home phone business. Though that wasn't the emphasis of the conference, which still focuses on the needs of the enterprise and call centers, the writing is clearly on the wall. SIP trunk connections are likely to find their way into end-users homes once businesses - a group that serves as the canary in the mine for most new technologies - have worked out the kinks.

Tomorrow, I'll talk about a product I saw at the conference that, at first blush, I wasn't sure I would find interesting when first invited to speak to the responsible parties. That product just so happens to come from Microsoft...and no, it isn't Office Communications Server (OCS).

Topics: Emerging Tech, Telcos

John Carroll

About John Carroll

John Carroll has delivered his opinion on ZDNet since the last millennium. Since May 2008, he is no longer a Microsoft employee. He is currently working at a unified messaging-related startup.

Kick off your day with ZDNet's daily email newsletter. It's the freshest tech news and opinion, served hot. Get it.

Talkback

24 comments
Log in or register to join the discussion
  • ahhh no mention of IAX(2)?

    IAX(2) is better than SIP... they just want to focus on what they have and not what they should be using.

    I cisco, but at times like this... it makes me wonder.
    Been_Done_Before
    • Telcos

      ...aren't making large investments into IAX (v1 or v2). That matters, I think, as unless meteorites clear the earth of incumbent telcos, they are going to have a large role in the definition of standards.
      John Carroll
  • RE: SIP is the future of telecommunications

    Yep, you can buy a Microsoft Response Point phone system from Costco call AireSpring for a SIP Trunk and off you go.

    Times are changing. This is a lot easier than it was when you had to negotiate for your phone system and then deal with AT&T.
    dustysage@...
    • VoIP CPE

      And where do you think your public phone number comes from?

      It's easy to own VoIP CPE. It's a lot harder to own an NPA-NXX.

      It's great that we have a large selection when it comes to PBXs, but the ILECs still own the public numbers. I don't see that going away for a very, very long time.
      C_T
  • Asterisk

    SIP is the future of telecommunications? John, that is too funny.

    [url=http://en.wikipedia.org/wiki/Asterisk_(PBX)]Asterisk[/url] runs on my business server for free and I register with [url=http://sipphone.com/]SIPphone[/url].

    For example, my Nokia N95, a SIP-enabled smartphone, acts as a remote extension, meaning that if a caller reaches my Asterisk business line's Voice menu and dials my internal extension, my N95 answers the call--ANYWHERE.

    Pick yourself up an unlocked SIP ATA phone adaptor, such as the linksys/SIPURA 2100-NA and you can set up your home with any SIP provider that supports 'bring your own device' (BYOD), [url=http://www.sipcenter.org/sip.nsf/html/Service+Providers]there are many[/url].

    If you'd like to use a SIP softphone on your PC/Laptop, Java-enabled phone, [url=http://gizmo5.com/pc/]Gizmo[/url] works well. [url=http://www.fring.com/]fring[/url] or [url=http://www.truphone.com/]Truphone[/url] are probably the best examples of Java-enabled cellphone SIP providers around. I use fring.

    Thanks for the heads up on SIP! ;)
    D T Schmitz
    • I'm well aware of Asterisk

      ...and have used it myself. It's a good product.

      However, I'm talking about telecommunications companies making end-to-end SIP architectures. Most telcos now have large investments in SIP. SIP is THE VOIP protocol.

      A big issue in SIP has also been incompatibilities in implementation. Standards like SIPConnect aim to rectify that.

      Like I said, SIP isn't anything new, and its role has been on a glide path to greatness for awhile. The difference, however, is the buy-in from telcos. That is what makes SIP THE protocol. Asterisk is interesting, but it isn't going to drive protocols. For instance, I don't thin IAX has a long future.
      John Carroll
      • Time will tell

        "For instance, I don't thin IAX has a long future."

        Unless you use trunking or multiplexing. IAX2 is very popular
        for these purposes and offers significant advantages over
        SIP.

        Whilst less flexible than SIP, IAX2 does have significant
        advantages and I'd be surprised if it disappears.
        Richard Flude
  • Surprising?

    "Tomorrow, I???ll talk about a product I saw at the
    conference that, at first blush, I wasn???t sure I would find
    interesting when first invited to speak to the responsible
    parties. That product just so happens to come from
    [b]Microsoft[/b]???and no, it isn???t Office Communications
    Server (OCS)."

    John reviewing a MS product, surprised?

    "John Carroll has delivered his opinion on ZDNet since the
    last millennium. Since May 2008, he is no longer a
    Microsoft employee."

    Right;-)
    Richard Flude
    • And you...

      ...have been complaining about my preferences even longer. I write about software, and what interests me, and clearly that includes a lot of the products created by Microsoft (hence my decision to work for Microsoft for three years). I have absolutely no idea where your interests lie, beyond hints that it is aligned somewhat along Mac development lines.

      But hey, you prefer the anonymity of talkback firebombs. I lay my entire background for all the world to see...and write for a rather well known technology news site (meaning I have to disclose a lot more than you do).

      Would be curious to see details about your own work history, though I am unlikely to get it. Everybody makes career choices based on what interests them. I've never been to a MacWorld conference...and you have. Bias, or just an expression of your own interests?
      John Carroll
      • Take it easy

        Didn't you know it? That's the way it is.
        You write for a known website, so you're supposed to be the one to disclose. Your readers and commenters are not.
        Also, you're the one supposed to be rational, cool and impartial.
        Commenters are allowed to be fans :)

        I read you because I find your articles valuable many times.
        But I also find that many times your infatuation with Microsoft is laughable.
        I think that it will make you a lot better journalist if you can get over it, and look at MS as they are, and not through your distortion reality mirror.
        dcardozo
      • For the record

        "Would be curious to see details about your own work
        history, though I am unlikely to get it."

        IT contractor for 20 years working in mainly in large
        enterprise IT operations (Lotteries, Defence, Billing, Retail,
        Call Centres, Telecommunications, R&D, Newspapers, one
        of the big three IT services companies).

        Rejecting the over reliance on MS technologies by the
        enterprise (irony was I designed and supported many of
        them - seems the MSCE isn't up to the task), I've spent the
        last years working on a number of smaller projects around
        linux in retail and media.

        Whilst I've developed for Macs (and keep up for fun), I
        spent my early career with C/C++ on VMS, then C and Java
        on UNIX. Now when coding I do embedded Linux (C), JEE
        and Flex RIA - but much of my work is design and systems
        integration.

        Like yourself I've lived extensively overseas (native
        Australian) in Europe and North America, and looking to
        relocate to Asia where I currently travel for work regularly.

        I've a degree in Computer Science, and a graduate diploma
        in Economics.

        I've rejected offers to partner with MS. The company's
        history on anticompetitive practices and ridiculously low
        level of contribution to the industry makes it impossible
        for me. Unlike some I'm unable to contort the truth
        enough, or overlook stuff for the money to find it acceptable. Over my career I've work with hundreds that
        have, but few I respected.

        Fortunately we've better alternatives today: *nix + Java for
        the enterprise, Mac OS X for the desktop, Linux for
        embedded. We're seeing the start of the move away from
        MS technologies and back to the reasoned positions of my
        early career before the destructive MS anticompetitive
        practices.

        "I've never been to a MacWorld conference...and you have.
        Bias, or just an expression of your own interests?"

        I've also been to many more MS conferences because as
        professionals we need to know what's going on. But
        anyone that has been to both would know only one has the
        feeling that they're part of something positive.
        Richard Flude
        • And when did you start exhibiting

          an arrogant and self-righteous attitude? When you did how did it go with your numerous (it seems) employers? Did they enjoy it?
          readwrite
          • I've found employers enjoy people that can do the job

            I've delivered 100% on past projects. Most are projects I've
            been brought in after they've gone bad. When they're done
            I'm out. I've always been asked to stay.

            I'm not sure what is self-righteous about taking a position
            against a company involved in illegal activities, but likely
            your morality is different.
            Richard Flude
          • There's nothing like listening to (or reading)

            somebody promote himself to size him up.

            I'm sure you believe everything you said and that's sad.
            readwrite
          • Happy to hear about your experience;-)

            Responding the JC request for my background to counter
            claims of my anonymity. Unlike many I've always posted
            using my real name, only suppressed client names.

            I'm happy from anyone I've worked with to counter my
            position.
            Richard Flude
        • So you're a 'nix guy

          Puts a lot of things in perspective, though it is always curious how some seem to think their interests don't have any effect on their decision to hate certain companies.

          I was a Java developer as well...maybe even as long as you have been (maybe longer...you still know more about me than I you). Didn't make me want to stick with Java, because as you are well aware, I don't think it is as good as .NET.

          But, you have your belief in the fundamental evil of the other side to keep you away from their toys.
          John Carroll
          • Right, Unix being the only MS alternative left standing

            "Puts a lot of things in perspective, though it is always
            curious how some seem to think their interests don't have
            any effect on their decision to hate certain companies."

            To be fair my opinion of MS was developing well before I
            became a *nix guy;-)

            I've been in IT long enough to have witnessed firsthand
            MS's effect on our industry and I can't say much of it has
            been positive. Opportunities are finally returning, and
            along with this come creativity.

            "Didn't make me want to stick with Java, because as you
            are well aware, I don't think it is as good as .NET."

            Which is fine. I've said repeatedly .NET and JEE are the two
            best technologies for the enterprise. For enterprise apps
            both solutions can deliver, though I'm on the JEE side.

            For desktop apps .NET is up against say Apple's Cocoa.
            You were quick to dismiss Cocoa without looking at it.

            Competition is returning to IT which is leading to massive
            advances across all sectors. I regularly attend trade shows
            throughout Australiasia and come away from each with at
            least a few very impressive ideas/products. Many of these
            products are being built of non-MS technologies. Very few
            are built on MS stuff, and I can't think of any in the last
            several years from MS itself.

            MS influence comes through it's money (of which it has
            plenty). Through this it gets press, mainly about nothing
            (rumours, talk and press releases).
            Richard Flude
          • And my opinion of MS...

            ...developed while I WAS a Unix guy. I remember my first job with a telecommunications related company (Nortel), where they asked which browser I prefered, IE or Netscape. I said Netscape, and gave a long list of reasons why I didn't like Microsoft.

            Of course, I had done almost zero in the way of Microsoft-focused development (well, not zero, but just far less than what I had done in UNIX). That quickly changed, and as I learned what Microsoft's development platform offered, I found I preferred it more and more.

            [i]I've been in IT long enough to have witnessed firsthand MS's effect on our industry and I can't say much of it has
            been positive.[/i]

            I've been just as firsthand, and I came away with a different conclusion. Perhaps I see the benefits of a platform model as popularized by Microsoft. Apple's approach certainly wouldn't have been conducive to the levels of innovation we saw atop the PC platform.

            I'm not going to pretend that Microsoft has been lily-white. As you may remember, I do support protocol documentation rules, as an example (that was the subject of the long letter I wrote to Kollar-Kotelly as part of the appeal). I also think its good that Microsoft offer hooks into their system that don't lock you into Microsoft inclusions.

            I do, however, recognize where Microsoft has done good things. You disregard most of those areas, and fixate on the negatives. In fact, given your strong antipathies, I would say you CAN'T see anything good about Microsoft systems. I, however, can see plenty of good things in the UNIX world, even if I prefer the Windows one.

            [i]For desktop apps .NET is up against say Apple's Cocoa. You were quick to dismiss Cocoa without looking at it.[/i]

            I've done more than look at it. I've programmed with it (though you probably still have more experience with it than I do). I still think .NET is many orders of magnitude better. That might seem inconceivable to you, but you strike me as a person convinced that everything they believe is objectively true.

            More is being done with non-Microsoft technology, to be sure, though then again, computing has crossed a threshold. It is now, literally, everywhere, and the market for software is so big that it would be very odd if one company continued to dominate as much as Microsoft did in the late 90s.

            Perhaps you just dismiss the Microsoft technology too quickly. This thread was started as you accused me of extreme bias by reason of my past employment (I seem to recall that before I went to Microsoft, you believed I was part of some vast Microsoft-funded conspiracy). Basically, you are saying: pay no attention to the arguments, because he used to work for Microsoft.

            The contrast, of course, is someone who thinks that Microsoft is morally evil, and thus won't even pay attention to what they are doing.

            Is Microsoft on the top of its game? Since you read most of my posts, you know I don't think so. On the other hand, I don't approach Microsoft products with such strong negative preconceived notions.
            John Carroll
          • dismantling preconceived notions

            "I still think .NET is many orders of magnitude better. That
            might seem inconceivable to you, but you strike me as a
            person convinced that everything they believe is objectively
            true."

            I try to give reasons for my opinions and provide links as
            often as possible. When I've been wrong I've posted
            corrections (VC1 licensing, HD-DVD, antitrust
            investigations, API consistency, anyone?).

            What about .NET makes it "orders of magnitude better"
            than Cocoa for desktop application development? Do you believe it's orders of magnitude faster to develop in? Is the
            API "orders of magnitude" more complete than Cocoa? Why
            doesn't MS use it for any of their major applications?

            This is what perplexes me. The only issue that appears a
            negative for Cocoa is memory management (specifically
            managed code memory management) and I can't see this
            is a big issue for desktop application development.

            Apple turns out more applications written in Cocoa than
            MS does in .NET with a fraction of the claimed R&D
            expenditure. How is this possible?

            "Apple's approach certainly wouldn't have been conducive
            to the levels of innovation we saw atop the PC platform. "

            Why? Apart from hardware, which MS contributed zero,
            what innovations are you talking about? The GUI, desktop
            publishing, non-linear video editing, web browsers,
            multimedia?

            "This thread was started as you accused me of extreme
            bias by reason of my past employment (I seem to recall
            that before I went to Microsoft, you believed I was part of
            some vast Microsoft-funded conspiracy)."

            Bias towards MS, leading to job with MS, post MS more MS
            articles.

            "The contrast, of course, is someone who thinks that
            Microsoft is morally evil, and thus won't even pay attention
            to what they are doing."

            I'm very familiar with MS technologies. I've had the benefit
            of using them for years before MS "invents" them;-)
            Richard Flude
          • To Flude

            [i]I try to give reasons for my opinions and provide links as often as possible.[/i]

            Oh really? I don't remember you as being a prolific link-poster. Yes, you do post link sometimes when you think the links are a slam-dunk, but more often than not, you just state things as facts as you see them.

            But then again, you are producing talkback posts. That is reasonable for a talkback poster.

            [i]What about .NET makes it "orders of magnitude better" than Cocoa for desktop application development? Do you believe it's orders of magnitude faster to develop in? Is the API "orders of magnitude" more complete than Cocoa? Why doesn't MS use it for any of their major applications?[/i]

            As you know, I am pretty new to Mac programming, so I'm not going to go into a blow by blow description. Right now, though, I can safely say that I'm no fan of Objective-C. I thought this quote from Hillegass was a nice way to spin a negative into a positive:

            "[i]Unlike C++, Objective-C is a weakly typed and extremely powerful. With power comes responsibility. Objective-C allows programmers to make ridiculous errors[/i]"

            Objective-C is powerful like Javascript is powerful. That doesn't mean I like doing lots of things in Javascript (granted, Javascript is far less typed than Objective-C). There's a reason, I think, why strongly typed languages won the battle for language supremacy, and I find having to step into a modified version of C particularly annoying.

            Personal, I think all the "flexibility" benefits can be managed in a strongly typed language with far less scope for developers to make egregious mistakes.

            Oh, and I also really miss generics.

            I'm also at a loss to see this amazing design excellence on the part of Cocoa. It's different, admittedly, and a lot more rigorous about imposing certain UI conventions. It certainly is an improvement over WIN32, but as I have made abundantly clear in a past post inspired by one of the times you did provide links, if you are still doing anything in WIN32, you are really stuck in a timewarp.

            But, I'll go into more detail once I'm ready. I'm sure you'll read and criticize it when I do.

            [i]Apple turns out more applications written in Cocoa than MS does in .NET with a fraction of the claimed R&D expenditure. How is this possible?[/i]

            And that is an issue that I talked about in a previous blog post (but you know that). I think it has a lot to do with momentum and a legacy of huge codebases not written in .NET.

            You may not realize how many applications are written in .NET. The Expression suite is being written in .NET. I know IPTV makes heavy use of .NET, with native code for the performance-critical bits.

            Apple does use Cocoa quite extensively, and that is to Apple's credit. Given the breadth of products in Microsoft's product catalog, I think you underestimate how much uses .NET. There is work involved in moving to the new architecture, but it is happening.

            [i]Why? Apart from hardware, which MS contributed zero, what innovations are you talking about? The GUI, desktop publishing, non-linear video editing, web browsers,
            multimedia?[/i]

            Innovation is more diffuse than that. I think the design of .NET is very innovative, and yes, it borrows ideas from Java, but then again, most UIs borrow ideas from elsewhere. Knowledge is an incrementally built mountain. I think it was innovative for Microsoft to opt to make IE an reusable set of components. That wasn't what Netscape was doing, and they created the market for browsers.

            When I talk about freedom to innovate, I'm talking about the fact that Microsoft created an environment where drops in hardware costs were possible. That simply would not have happened had Apple had a 90% market share. There's less reason to drop costs if Apple isn't competing with anyone else.

            Microsoft is not a hardware company, to be sure. But their licensing model created a situation where hardware companies competed to lower costs. Creating an effective market is important, and Apple, historically, has been less good at that.

            [i]Bias towards MS, leading to job with MS, post MS more MS articles.[/i]

            Bias based on experience, if you can call that bias. You have spent a career in computing and concluded that UNIX is the better way to go. Good for you. By the previous definition, are you not biased?

            I happen to be a strong fan of free markets. That makes me less likely to accept arguments made by those who think it a good idea to close america's markets to imports. Is that bias, or just the end product of a life spent thinking about the issues?

            [i]I'm very familiar with MS technologies. I've had the benefit of using them for years before MS "invents" them;-) [/i]

            You've said nothing that leads me to believe you are an expert in .NET programming, or Windows programming in general. But, we can't have a programming contest online to verify things.

            You pursue technologies that fit your worldview, which is that Microsoft is evil, and UNIX is better. Everyone does that, to a certain degree (though not everyone concludes one side of the contest is "evil"). I, for instance, am finding that I have a waning interest in writing applications for the iPhone due to the need to run the approval gauntlet for anything I write. I find that a bit too controlling. I like the open market approach to software development, which is the one used more often by Microsoft and the open source community.

            Maybe that is akin to your inability to see Microsoft as possessing any sort of redeeming qualities.
            John Carroll