The First IMS AG Face2Face Event is Here

By Tsahi Levent-Levi

It’s about time this happened. We’ve been working for several months now in the IMTC IMS AG for this moment – the first face-to-face interoperability event of our group.

Why is this important?

Up until today, no real IMS testing was done for the client side in any methodical way. Sure, the IMS Forum is doing PlugFest events and the GSMA is also doing some basic interoperability testing for their specification. Nevertheless, there’s no real place where handset vendors and middleware/software providers for handsets can gather around on a regular basis and deal with interoperability. The IMS AG is just that place.

What do we focus on?

We currently deal with Video Share as an IMS service that we are testing, focusing on the client itself. Not what is required on the network side and how billing is done but rather how two mobile clients can call each other, negotiate the parameters they will use for the call and share a video session between each other. We will be moving on to additional client-side service aspects as they develop – we started with Video Share simply because it seems like one of the services of IMS that will be deployed first – I believe AT&T is the first of many operators that will focus on Video Share in the next couple of months.

What do we do?

We talk once a week or two, depending on availability. Companies in the group join a conference call to discuss matters at hand. In these calls we discuss a wide range of topics:

• Drafting out our test case document
• Establishing and discussing liaison connections with other organizations (GSMA, IMS Forum, OMTP and others)
• Scheduling interoperability events

Our goal?

To make sure that once operators decide to deploy services such as Video Share, they will be able to choose any phone vendor they want and be confident of the level of interoperability provided. This means that operators would rather take handsets from vendors who are actually test interoperability in the IMTC IMS AG.

October interoperability event

Our first event is scheduled for October 10-12 this year. RADVISION, my company, is hosting this event along with the 3G-324M AG, which will do their own interoperability testing there.

We are planning to convene after the event and publish the first official test cases document for Video Share from the IMTC. As usual, I am sure we will have some comments to the 3GPP and the GSMA that might require some clarifications or changes to the specifications – that happens when an activity group in the IMTC starts doing interoperability and places a specification under its magnifying glass…

If you do develop communication products, you must know that interoperability is important. What do you do to close this gap of interoperability in your products?

Technorati Tags: IMTC, IMS, IMS Client, Video Share, GSMA, IMS Forum, OMTP, 3GPP, Interoperability, 3G-324M, Tsahi Levent-Levi

H.323 versus SIP: An (un)objective Comparison

By Tsahi Levent-Levi

I came across an interesting comparison between H.323 and SIP in a Cisco related blog. They make a pretty good technical analysis, but the comparison lacks in its completeness.

Both H.323 and SIP are used today for VoIP, and they are considered interchangeable solutions. The comparison made covers the following issues:

• Philosophy – H.323 does calls, SIP does sessions
• Reliability – H.323 reliable by design, SIP by responsible user agents
• Message Definition – H.323 uses ASN.1, SIP uses ABNF
• Message Encoding – H.323 is binary, SIP is mostly textual
• Media Transport – both use RTP/RTCP and SRTP
• Extensibility – H.323 extensible by design, SIP breaks interoperability with extensibility
• Scalability – H.323 scalable by design, SIP by implementation or by additional IETF standards
• Addressing – H.323 supports multiple addressing schemes, SIP has only URIs
• Billing – H.323 has billing by design, SIP by implementation

And the list goes on to other issues. It seems strange to me that in all, H.323 either excels or does as good as SIP. This being the case, why does every new developer looking for SIP?

I have been working with H.323 and SIP for several years now, and I can say that both have their advantages and both are broken in some places. H.323 is a lot better today in issues of interoperability – a lot of it can be easily attributed to the IMTC’s work in this area. I also have a warm place in my heart for this particular protocol – I have been working and dealing with it for many years. That said, the comparison above lacks two main points:

IMS

The 3GPP’s next generation network, which has been adopted by the Tispan and CableLabs (making it the de-facto network in the world in the future). This happened as the 3GPP added interfaces scenarios and call flows to SIP, giving more advantages to it.

H.323 is not part of IMS and is irrelevant for IMS.

SIP is at the core of IMS.

Market

H.323 is dominant today and has large deployments around the world. It is a lot better where it comes to video conferencing, and can be found a lot more in the enterprise.

SIP is the protocol of choice for most developers today – it is quite strong in the consumer and service provider markets. If you are a company about to develop a communication product, you will probably be selecting SIP. It is not as good for video conferencing, but it is getting there.

Services

There is another parameter that is important, and that is what services are part of the protocol and what new services can be offered easily?

H.323 focuses on multimedia calls in all of their flavors. Voice only, video, data collaboration, conferences and a rich set of telephony services.

SIP doesn’t seem to focus on anything in particular. You can use sessions to make calls with it (voice, video – whatever), you use it for presence and instant messaging, and you can use it for a large array of additional services as well.

That said, these services can be added to H.323 as well – this statement would be true to trying to add new services to SS7 though…

Now, if you opened a company now, which protocol would you decide use? What would be your decision looking only on technical aspects, and what would it be looking only on market aspects?

Technorati Tags: Cisco, IMS, IMTC, H.323, SIP, VoIP, Interoperability, Tsahi Levent-Levi

IMS, 3GPP and IETF: A standardization complexity

By Tsahi Levent-Levi

How do we get those specifications for IMS? In a complex way.

It started off as a set if requirements for a Next Generation Network (NGN). The 3GPP wanted an all-IP network for its mobile infrastructure, calling it IMS (IP Multimedia Subsystem). As there’s no need to reinvent the wheel, the 3GPP decided to select an existing standard to do the work, and SIP was there – all young and fresh. But SIP is an RFC. It is handled and standardized by the IETF. This need not be changed.

So what does an organization like the 3GPP does at this point in time? Use the IETF as a subcontractor.

Have you ever worked with a subcontractor? I have never heard of anyone who liked the experience… you provide requirements for a rocket to space, and you get a fire cracker. You want a match, and you get a rocket instead. Time is not time, effort estimations are far from true (sounds like regular development, but it is always harder with a subcontractor).

So we have the 3GPP providing the requirements, while the development of new RFCs (=standards for IMS) done by the IETF, including modifications to RFCs when needed.

The result?

• We have a whole lot of RFCs coming from the IETF. Some colliding each other, others solving the same problems, but a bit differently.
• We have a bunch of 3GPP specifications, which point to RFCs (and a lot of drafts!) that are used by the 3GPP’s IMS network – in a way, a selection of the RFCs that are needed.
• But then, it is not always understood which features from the IETF, or the 3GPP you really need to build an application. And as usual, I haven’t covered GSMA, GCF, OMTP and other organizations.

We at the IMTC IMS AG are actually facing these issue each day. We are currently unraveling the set of specifications required for the implementation and interoperability of the Video Sharing service that is gaining momentum.

Technorati Tags: IMS, IETF, SIP, SigComp, 3GPP, Standardization, Tsahi Levent-Levi

IPSec - transport and tunnel modes

By Tsahi Levent-Levi

Remember my post about IMS access?

I talked about how a user is authenticated on the network using a key exchange mechanism (AKA-MD5 or IKE) and IPSec to ensure privacy.

We were left with this one nagging issue derived from the fact that IPSec is used differently with different types of access. These are:

1. Transport mode, when we use IPSec with AKA-MD5, and we have a USIM.
2. Tunnel mode, when we use IPSec with IKE, and we don’t have a USIM.
3. Transport over tunnel mode, when we use IPSec twice, since we’re outside an operator network.

Why is there a difference? Why not have IPSec in a single mode (like IP VPN) and be done with it?

Well, let’s start with tunnel mode. In tunnel mode, the data that you want to send is going to be passed “as is”, with the key exchange done using either IKE or MOBIKE. That’s not good enough for our USIM (the one that requires AKA-MD5, as it makes more sense to manage the data in front of the operator’s HSS). AKA requires exchanging keys and tweaking some internal parameters of IPSec. So we need to use a different mode for IPSec in this case. The problem is, some of the operating systems most commonly used in mobile handsets do not support this mode. So there is no real solution today for developers. Hopefully, solutions will become available soon.

Doing IPSec twice is sort of like peeling the layers of an onion. The external layer is tunnel mode, where you use IKE in front of your wireless network’s access, but then tunnel the IPSec packets generated using transport mode, which were generated with AKA-MD5 to authenticate the USIM you have with the mobile network (since you don’t have direct access to it) inside it.

So IPSec alone is also an issue.

Do you think this post was written just to make you developers despair? Nah… I know you guys. I am one of you. We developers love challenges. We thrive on them. And IMS is a doozie!

Technorati Tags: IMS, SIP, IPSec, Tsahi Levent-Levi

AT&T and Video Share

By Tsahi Levent-Levi

I totally missed this one!

I’ve been to NXTcomm. I sniffed around. I searched for IMS. I came back empty handed.

But then – AT&T actually announced their Video Sharing service during the show. And on the same day I was there…

I first found out about it in MobileCrunch blog – good I’m reading others. Two days after it was posted there, my Google alerts went jiggling happily about this service. It’s so good to know that operators are going to offer Video Sharing as their first IMS service.

To those of you who don’t know what Video Sharing is and those who would like to understand what can be done with this technology, AT&T were kind enough to have some mockup demos in their site – they’re quite good.

The interesting this is that they will be doing that over their WCDMA network and not CDMA2000 EV-DO one. The reason for that is the way these two technologies differ from one another.

In WCDMA, you can utilize both the circuit switched and the packet switched networks at the same time. This means that you can do an audio call over the circuit switched connection (as it is done for every audio call today), and then you add the video over the packet switched network (the data capability of the network).

But in EV-DO, this is impossible. You either do voice calls over circuit switching or data of some kind which would be packet based. So to do Video Sharing over EV-DO would require doing the voice over IP as well – and that’s a whole different ballgame.

So Video Sharing it is.

Let’s see which operators jump on this one next.

Additional coverage - Wired News, AT&T Site

Technorati Tags: NXTcomm, Video Sharing, IMS, Tsahi Levent-Levi

NXTcomm and IMS

By Tsahi Levent-Levi

This week I had a business trip. As part of my day job, I joined a panel discussing the IPTV experience at NXTcomm. While there, I had the time to walk around the show floor and see what companies are doing.

I can definitely say that this year, the main theme of NXTcomm is IPTV.

The second coolest acronym in the show was IMS.

First question out there, is what does IPTV has to do with IMS? Probably everything and nothing at the same time… But I’ll be leaving this one to a future post sometime.

What I really want to discuss here is still IMS.

Walking the floor and talking to companies in NXTcomm means you are meeting a lot of sales people from different companies. So IMS is what I do here, and I decided to go check what these people know of the IMS offering of their companies (you know – it’s not that easy).

Here’s a short roundup of the answers I got:

• “It’s essentially SIP”
• “We’re doing SIP, connecting it with Alcatel-Lucent’s thing, and we support IMS this way”
• “We’re IMS-ready” (heard that one before)

So nobody really knows what IMS exactly is there and don’t know how to chew it. Hopefully, this will change with time… especially when they all have IMS written all over their booth…

Technorati Tags: NXTcomm, IMS, IPTV, SigComp, Tsahi Levent-Levi

Testing IMS Video Sharing in the IMTC's SuperOp!

By Kristofer Jarl

Hello friends.

I'm now facing a difficult task. I have to write enough material about our tests during SuperOp! 2007 to make this post interesting, and at the same time I have to keep the actual result and outcome secret, due to disclosure agreements. Let's see how I do.

First of all, there was no scheduled test time dedicated to CSI (or VideoShare) during SuperOp! 2007. The testing we did was outside ordinary schedule. But still, we received lots of help from the fine people arranging this event, setting up environments, provisioning SIMs and so on. Thanks to everyone who helped out.

After having tested connectivity and server environments during Thursday evening, the actual testing began early Friday morning. A few hours later, we were forced to cut off, since networks were going down and plugs were being pulled. Nevertheless, we are happy with the outcome. We have tested according to the test specification, and we have some issues that should be addressed. Video has been sent, and video has been received.

Saturday morning we had our first F2F meeting. Finally. Due to some last minute changes, only five companies were represented. But we are still satisfied, we now have momentum. Several details were discussed regarding the test document, and we started planning a new test activity sometime during August/September. This time it will be an isolated CSI test activity. We will focus solely on the services that the group is involved in. Sweden or Israel seem to be hot candidates. Hope to see you all there!

All in all, it's great to see the recognition we are gaining, after all our hard work. If we keep going like this, we are on our way to success. New companies are joining the group, and our liasons are welcomed by everyone. Hopefully, more test events will be reality soon, and we are also glancing at other features similar to CSI that we would like to bring into our group. Please join, you could be in for something good!

Take care!

Kristofer Jarl
Sony Ericsson Mobile Communication

Technorati Tags: IMS, SuperOp, Video Sharing

IMS and access

Let's explore the issue of access (how IMS clients register on the network and gain access to services) in the world of IMS. Today, the way this is done over UMTS is simply by using the USIM (that small card hiding behind the battery of your handset. You know; the little bugger that falls out of the phone and onto the floor sometimes).

The USIM card is what holds the information that links your identity with the mobile operator’s database. And that’s what it does on an IMS network too.

So what do we need to do? Connect a mobile handset that has a USIM to the network. The technique used is asymmetric keys, exchanged in SIP, using a procedure called AKA-MD5. And since we want the actual exchange of the information to be secure, we send everything on top of IPSec, in a mode called transport mode.

Sounds OK. But that’s the 3GPP way of doing things. IMS has been adopted by all sorts of networks, and all types of Wireless LANs (WLANs) will now used as access to IMS infrastructure.

But wait – WLAN devices don’t have USIMs. And no asymmetric keys you can use directly. And you still need authentication. Maybe the solution is to use IKE! -- not AKA-MD5. And why not use IPSec – we have that already. And once we are doing that, we should use a different mode of IPSec (tunnel mode if you’re really into details).

Let’s see… can we make it even more complicated? What about all those mobile devices that have both USIM and WLANs. OK, here’s a neat solution. Let’s do IPSec twice (yes – twice!) on each and every packet we send. One will provide access to our WLAN network, and this will tunnel IPSec packets that are targeted directly at the IMS core of the mobile operator. So lo and behold, now we are going to have transport level over tunnel for IPSec!

Confused? Well, so am I.

And as if all this wasn’t enough, I haven’t even gotten into all the veritable alphabet soup of other issues like MOBIKE, EAP-AKA or EAP-SIM. Ouch!

To make a long story short, this may sound and look unwieldy. But it works.

When you are developing new products, don’t forget that gaining access to IMS can be quite a complex task. It depends on which transport you are using and what network you are trying to access. So roll up your sleeves, get out your acronym glossary and get to work!

Technorati Tags: IMS, SIP, 3GPP, IPSec, Tsahi Levent-Levi,

IMTC panel at VON Europe - IMS, Enterprise Communication and Carriers

Next week, at VON Europe, I will moderate an exciting panel about the influence of IMS on the business of enterprise communication vendors. The panel will take place at the exhibition theater, 12th of June, at 1145.

The panel will cover, among other issues:

1. The evolving needs of enterprise customers

2. The way IMS opens the enterprise communication market for operators

3. Business strategies and positioning of different market players

Our panelists include:

Stefan Karapetkov, Sr. Techinal Advisor, Polycom

Edmond Osstyn, Business Development Director, IMS Applications, Alcatel-Lucent

Adi Paz, Sr. Director, Products and Marketing, Radvision


Technorati Tags: IMS, VONEUROPE07, Polycom, Alcatel-Lucent, Radvision, Kfir Pravda, Strategy, Enterprise communication, carriers, operators

Compression and IMS, Part 2: ROHC

In my last post, I discussed SigComp and how it relates to the wonderful world of IMS. SigComp though is only part of the IMS compression story. There is more. Much more.

Just in case you forgot – messages are big. We would all like to shrink them so that they use less of operators’ precious bandwidth. We tackled the big message problem by compressing the content using SigComp.

But there is one “minor” issue I left out last time – the issue of IP. IP is a nice enough protocol, and is required for IMS (you remember the IP Multimedia Subsystem…).

SIP messages are sent over TCP or UDP, which in turn are sent over IP. RTP packets (you know, that media we want to see or use) are sent over UDP, which again means it is over IP.

Last time, we dealt with the SIP message issue. But what about the IP, UDP, TCP and RTP?

All these have their own headers that add lots of overhead to the messages themselves. We’re talking about 40 bytes for an IPv4 packet sent over RTP (UDP and IP included). And if we have to send 50 of those packets every second just to keep our audio running, we have some pretty heavy packets to deal with!

The solution to this problem is ROHC (Robust Header Compression). It is defined in various RFCs, with different modes of operation. I won’t delve into the technical details, but would like to point out one very interesting thing: it’s in the operating system.

Since ROHC is used to tweak the size of IP, UDP and TCP headers and compress them to be 1 or 3 bytes, it requires support from the operating system itself. By operating system, I mean your “average” IP stack that you get for free with it.

What all this means to us, is very simple. To implement IMS – and on a client no less – requires not only application implementation but also an operating system with support for all the architecture’s special needs.

Technorati Tags: IMS, SIP, SigComp, 3GPP, Tsahi Levent-Levi, IMTC

Compression and IMS: SigComp

By Tsahi Levent-Levi

I have been promising to touch on the different aspects of technology related to IMS, and if there is one thing I am good at – it is keeping promises! This time I will start with one of these – compression.

For all you history buffs, let me take you back in time a bit. Once upon a time, there was a great protocol named SIP. It was simple (yeah, sure!) and easy to use. It was text based (Look Mom… you can see messages!), so it was easy to implement, maintain and debug. Many people started to use it and promote it big time. And it did have some great routing and filtering criteria capabilities. So at some point, the 3GPP decided to adopt it for IMS.

So the world was a better place with a nice, simple, text-based protocol, used for signaling purposes over mobile networks. And since it’s signaling, and you don't have a lot of information you need to convey, it should work. But as time went on, people saw that the messages and the amount of information were actually quite large. When you start adding routing information, authentication and authorization information, billing information and some more – each message becomes REALLY big.

At the end of the day, we had a text-based protocol, with large messages, running over mobile networks. Our problem: mobile networks have lower bandwidths than fixed IP networks (mostly). Also operators out there have to actually pay for the bits you use. For them, more bandwidth required per user for simple calls means less capacity in their cells… and more power consumed by the handset which means a shorter battery life. What to do?

Zip!

You take those messages; you somehow “zip” them and then send them on their way when they take up less space. Since it’s text, it zips quite well.

The secret behind this “zipping” is with a compression protocol called SigComp (RFC 3220, and more) – Signaling Compression.

Everyone agrees: SigComp is nice. It’s general purpose, and it can use different compression algorithms. You can optimize it for the exact messages and scenarios you use. But it’s complex…

By complex I mean that SigComp actually uses bytecode methodology. When you compress messages, you can send along the code that is used to uncompress the messages with the compressed data. This is done using the predefined UDVM (Universal Decompressor Virtual Machine) instructions set (hence bytecode) that outlines the different atomic operations allowed in SigComp.

The process is fairly easy. To compress, you choose an algorithm, use it for your compression, send the compressed data along with the algorithm, and the other side uses the algorithm you sent to decompress.

To make things even more interesting, there’s also a dynamic version of SigComp, which lets you update the SigComp states used in mid-session to provide optimized compression as well.

But then, what could you use as a compression algorithm? Would you go for an LZSS or a Deflate one? Would you do the dynamic optimizations with it? Do you go to patented compressions? Have you thought how much MIPS will this thing take on your mobile???

Lots of questions, huh?

So we have the IMS (3GPP that is). 3GPP means mobile networks. It also means limited bandwidth and the need to compress.

Remember though… there are other standards bodies that do not necessarily need compression, but have adopted IMS architecture. TISPAN and PacketCable, for example, are focused on the wireline and cable telephony networks. So our efforts in this area really are a wider attempt to build a single paradigm for all types of telephony and services! A virtual Utopia! Where everything looks the same.

But our friends who are adopting TISPAN and Packet Cable took a peek at our SigComp in IMS and said, “Sorry. We don’t need it.” Their networks can handle large messages, for them, adding SigComp just adds complexity and requires even more resources.

So, on top of everything else, you are faced with the million dollar compression question: Do you need SigComp or not?

Oh yeah… and what about WiMAX?

So you see, SigComp is only part of the compression story. Next time, we’ll discuss other IMS compression issues.

Coming soon… IMS or “IMS-ready” – You CAN tell the difference!

By Tsahi Levent-Levi

In my first post on this blog, I started to explain the real difference between real IMS and “IMS-ready” or “IMS-lite”. In the context of SIP, which is what IMS is all about on the client side, this comes down to an exhaustive, daunting list of features. I know, I know... it is not all SIP. You also need IPSec, XCAP and other such curses. Don’t worry, I won’t forget them.

So to be sure I have enough to write about here, and because I feel that we really do need to understand the difference, I’ll be going over this feature list according to subject: compression, security, quality of service, billing, etc.

Because this is going to take some time, I will try to cover one concept in each post – so stay tuned!

I’d like to wish all our Christian readers, a Happy Easter and all our Jewish readers a Happy Passover. And to the rest of you… try not to work too hard while everyone else is celebrating!

What is your client strategy?

By Tsahi Levent-Levi

Whenever I visit customers in Asia Pacific, it always amazes me how different companies that are developing the same product can go about it in so many different ways. OK, maybe not exactly the same product. One handset weighs in at 170 grams and their competitor’s handset at 164 grams. One handset could also have a metallic color, and the other shiny gray. Go figure.

In trying to understand this phenomenon, I came to the conclusion that all these different approaches are a result of a fundamental difference in R&D philosophy.

Let’s assume you are a developer, and you have been given the daunting task of developing a mobile handset. And YES; it should be an IMS handset. The applications you need to support promise you a major headache:

- VoIP calls (audio and video)

- Presence

- IM (Instant Messaging)

- VS (Video Sharing)

- VCC (Voice Call Continuity)

By the time you’re finished, you assume the whole world speaks in “acronym”…

And now for the 50 million dollar question: How would you approach this development task?

Rest assured I won’t let you think too much while reading this post. Take it from me… I’ve seen primarily two kinds of companies – the “top down” kind and the “bottom up” kind.

Essentially, if you need to build an IMS client (that’s a mobile phone that does IP), first and foremost you need a solid SIP IMS implementation. Not your average-Joe “IMS-ready” or “IMS-lite” one. You also need engines for all those fun applications that will enable you to do VoIP calls, presence, etc. And to top it off, you need a user interface that can be stitched into Windows Mobile, Symbian or whatever operating system you’re using.

Illustrating it in a diagram, you get the following result. If you are one of those “bottom up” companies, then you believe that infrastructure is the key. You search for the right SIP stack, with all those nasty IMS extensions. You make sure your RTP implementation can handle all those necessary bandwidth and retransmissions for IMS. And you select a good codec vendor that can deliver on the promise of encoding H.264 in CIF resolution using only 80 MIPS (I wish…). Once you have that part figured out, the next step is to look for the engines you need to build your applications!

If you are one of those “top down” companies, you believe that the world is a set of applications you can mix and match… and all is well in the land of computing. You see SIP, RTP and those codecs as commodities. And for you, IMS is just another one of those things that you’ll figure out in the future. So out you go to seek your fortune in the market. You find a slick brochure of engines and applications, and choose what looks nicest. Presto! You have a really cool demo application running that really works. Until you look under the hood or try to plug it into a real network with other users.

In case you haven’t figured it out, I tend to side with the “bottom up” guys. I’ve seen too many projects leave the gate and start out running too fast… just to find out (pretty soon) that they were heading in the wrong direction. And now they are left with a lot of catching up to do.

What kind of company do you work for?

It’s always the same - Standards, Interoperability and Expertise

By Anatoli Levine

I’m very excited to be the first to welcome you to the IMTC Blog! As a popular saying goes, it is hard to teach old dogs the new tricks. IMTC is 14 years old, so in the terms of age technology, it is quite an honorable age. A lot of young engineers today might even question the sheer existence of the standards IMTC was all about. However, IMTC as an organization is evolving, and we do “learn new tricks” and reinvent ourselves. We moved from H.320 to H.323, then to Packet Switched, SIP and 3G Mobile Video. We continue evolving further to IMS and Content Delivery.

IMTC managed to build an incredibly valuable collection of standardization-related documents for such technologies like JPEG (we call this collection a Historical Archive). While organization evolved, the core things IMTC is all about stayed the same – standards, interoperability and expertise.

IMTC always advocated multimedia communications technologies based on open standards. The focus of the IMTC work is Real Life Interoperability. With numerous Interoperability testing events, including the flagship annual SuperOp! event, IMTC is well known in the industry as leading authority on interoperability testing. And with IMTC Forums, we always bring together world experts in multimedia communications and standards development. And this combination of expertise and leadership makes me believe in exciting future prospects of IMTC.

I do like science fiction a lot. While driving today to work, I was thinking about predictions made in the books about the ways we will communicate. And one thing did strike me is that almost everything which was dreamed of, except may be “Beam me up, Scotty”, is the reality today. We can see and hear each other any time any place, we always know our exact location, our cars can park themselves...if you are a science fiction writer, what kind of communication technologies will you envision? Well, I’m sure, whatever we will come up with, IMTC will be around to make sure it is interoperable and to promote it.

And while the new technologies are being invented, IMTC is continuing on its current way, and inviting you to join in. Next week at VON in San Jose, IMTC puts together a panel of experts who will discuss the role of standards in the today’s communications world. More info is available here: http://www.von.com/schedule_gcs31168946047.html

Then in April, IMTC members will get together for annual SuperOp! 2007 event ( April 23-27, in Jesi, Italy), to test all the latest developments in SIP, IMS, 3G-324M, Packet Switched and other technologies. And of course we have more events planned throughout 2007 and beyond. Bottom line is very simple – if your company is not a member of IMTC yet, make it high priority to join IMTC and help shaping the future of multimedia communications!

Have a great interoperable communications day!

There’s a new IMS AG - A new warm and toasty place for IMS client developers

By Tsahi Levent-Levi

You’ve probably already heard about IMS (and no, I am not referring to the Institute of Mathematical Statistics), and if you haven’t it’s about time!

In a way, IMS is all we ever wanted out of a communication system but were always afraid to ask for. It can handle services – intelligent ones, which traverse through several, different application servers. It can do billing. It is flexible. But it is also complex. Very complex. And at the heart of it there’s SIP – the text-based VoIP signaling protocol.

In its present state, IMS requires a large set of protocols. For SIP alone you will need SigComp, and Offer-Answer model, and Preconditions and P-headers, and new authentication and authorization mechanisms. And that’s not all. Since this requires a huge amount of work, the industry has come up with a new term for “wannabe IMS” companies that are currently deploying SIP and want to migrate to IMS: “IMS-ready.” By calling their products “IMS-ready,” what are they really trying to tell us? “Well, I have SIP, and I really want to do IMS… and since SIP is part of IMS, I am ‘IMS-ready.’” This means that sometime in the future they will get around to developing all those nasty IMS components that are missing.

If you think that this is all there is to it, then you’re quite wrong! If you have an IMS-compliant (NOT “IMS-ready”) solution on a SIP IMS User Agent (that’s a client), you also have a lot of applications running there. These can be VoIP, Video over IP, PoC (Push-to-X), Presence, Instant Messaging and maybe more. Each one of these is a world of its own, with a set of rules that are specifically tied to large number of standards – some of which are not even finalized! So your world as a client developer is a rather challenging one indeed!

How can a frazzled client developer possibly stay on top of all this? You can join the IMTC IMS Activity Group – a new “home away from home” especially for IMS client developers.

For years, the IMTC has been working on interoperability of multimedia technologies. I have been a part of this myself, as a co-chairman of the 3G-324M AG (Activity Group) for several years – in the good old days when video on 3G handsets was only in its infancy. Our 3G-324M AG has done some great things, and we still are, making sure that new handsets can talk to one another with video over circuit switched connections.

Now the IMTC has decided to open a new Activity Group to deal specifically with IMS interoperability issues on the client side – to help all those mobile handsets, wireless PDAs and wireline phones that want to be IMS clients. Not “IMS-ready” – IMS-compliant.

The bottom line: If you are doing IMS, and you are developing clients, the IMS AG, is the place for you. I’m the co-chairman and I can tell you that companies like Ericsson, Nokia, Sony Ericsson and Samsung are already there. So come and join us!

Glossary

SIP

SIP (Session Initiation Protocol) is an IP telephony signaling protocol developed by the IETF. SIP is a text-based protocol that is suitable for integrated voice-data applications. SIP is designed for video, voice and data transmission and uses fewer resources and is considerably less complex than H.323.

VoIP

VoIP (Voice Over IP) is a set of technologies that enables voice, data and video collaboration over existing IP-based LANs, WANs, and the Internet. VoIP uses open IETF and ITU standards to move multimedia traffic over any network that uses IP.

MIPS

MIPS (Millions of Instructions Per Second) is a measurement generally used to describe the speed of computer systems, and in some cases, the speed of a given algorithm or program. As a rule of thumb, lower MIPS for an algorithm’s implementation is desirable when used in mobile handsets with limited resources and battery life considerations.

RTP

RTP (Real Time Transport Protocol) is an IP protocol that supports real-time transmission of voice and video. It is widely used For VoIP. RTP is sent over unreliable communication channels, where data may be lost, delayed or re-ordered.

H.264

Also known as MPEG-4 Part 10, or Advanced Video Coding. H.264 is a digital video codec standard which is noted for achieving very high data compression. Technically identical to the ISO/IEC MPEG-4 Part 10 standard (formally, ISO/IEC 14496-10).

CIF

CIF (Common Intermediate Format) is a standard video format used in video conferencing. CIF is defined in a resolution of 352 by 288 pixels.

3G

Third Generation Mobile System – The generic term for the next generation of mobile wireless communications networks.

PSTN

PSTN (Public Switched Telephone Network) is the worldwide voice telephone network. Once only an analog system, most telephone networks today are digital. In the US, most of the remaining analog lines are the ones from your house or office to the telephone company’s central office.

SigComp

SigComp (Signaling compression) is a specification defined in RFC 3320, which enables compressing messages generated by application protocols such a SIP.

IMS

IMS (IP Multimedia Subsystem) is a standardized Next Generation Networking (NGN) architecture for telecom operators that want to provide mobile and fixed multimedia services. It uses a VoIP implementation based on a 3GPP standardized implementation of SIP and runs over the standard Internet Protocol (IP). It supports both packet-switched and circuit-switched existing phone systems. The aim of IMS is not only to provide new services but all the services, current and future, that the Internet provides. IMS uses open standard IP protocols, defined by the IETF. IMS truly merges the Internet with the cellular world; it uses cellular technologies to provide ubiquitous access and Internet technologies to provide appealing services. Because it is access network independent, IMS enables converged fixed mobile network.

TISPAN

Telecoms & Internet Converged Services & Protocols for Advanced Networks. Formerly Telecommunications and Internet Protocol Harmonization Over Networks (TIPHON) is a standardization body of ETSI, specializing in fixed networks and Internet convergence.

3GPP

3GPP (Third Generation Partnership Project) is a body comprising several organizational partners working to produce technical specifications for a third-generation mobile system based on GSM core networks and the radio access technologies they support known as WCDMA (UMTS).

WiMAX

WiMAX (Worldwide Interoperability for Microwave Access) was defined to promote conformance and interoperability of the IEEE 802.16 standard. The Forum describes WiMAX as “a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL.”

XCAP

XCAP (XML Configuration Access Protocol) allows a client to read, write and modify application configuration data, stored in XML format on a server. XCAP maps XML document sub-trees and element attributes to HTTP URLs, so that these components can be directly accessed by HTTP.