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

Would you like to meet F2F in the Holy land?

By Oren Libis

On October 8 -12, the company that I work in, RADVISION, is going to host the next IMTC 3G-324M AG F2F event in Tel-Aviv, Israel, and I am in charge of the organization of the event. This is not the first time RADVISION organizes such an event. The first event took place on February 2006 and yet the upcoming event is exciting just as much and even more.

I participated in many IMTC F2F events in the past 5 years and I traveled to many countries but hosting an event in your home country is completely different feeling. The fact that many people from different companies, countries and cultures get together in one place and work together is something wonderful but when it happens in your home field it is even more wonderful.

I very much enjoy hosting these people which I consider friends, telling them about my country, showing them the holy places, elaborating on the local customs and introducing them to the local food. This is amazing time and again to see their reaction to that. This makes me very proud in my country and very enthusiastic to show more and more.

In the previous event we visited in the holiest place in Israel – Jerusalem. This time we are going to visit in Caesarea. Our goal is to improve the hosting from event to event and so we have some more surprises this time that I am not going to tell otherwise I will spoil the surprise.

And yes, we are even going to work here between visits and test 3G-324M devices. But, I am sure that the special atmosphere and the activities around the event will ease the pressure of the work and make it more pleasant.

I hope that more and more people even from companies outside IMTC read this post and decide to join the event. I hope to see you F2F next month in the Holy Land…

Technorati Tags: 3G-324M, F2F, IMTC, RADVISION, Oren Libis, Interoperability

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

Will 3G-324M MONA be here this Christmas?

By Oren Libis

MONA (H.324 Annex K), the chosen call setup time reduction technique, was approved by the ITU-T and 3GPP over a year ago. How come we don’t see it in the market yet? It is mainly an issue of standardization and timing.

From past experience in 3G market, it takes about 6 – 12 months since a company has a prototype till the first model gets into the market. This happened in other standards and it has happened in 3G-324M time and again – WNSRP and channel negotiation conflicts are examples of this.

During this time many 3G-324M terminal vendors are working vigorously and intensively on their MONA implementations. Some of the implementations are more mature than others but all in all there is much more work to be done.

Implementing is not enough – you now need to test it. Most of the testing sessions are conducted in the 3G-324M Activity Group Face2Face events of IMTC. In these events many vendors perform interoperability testing against others but this is not that easy for new standards. H.324 Annex K is quite a complicated technique, which changed significantly the way 3G-324M call setup was done till now, so one can expect many interoperability clashes in the beginning of the testing – we’ve seen those in the last three events already. Obviously, the prototypes also need to maintain a very high level of interoperability with legacy terminals which makes it even harder. However, the interoperability level gets improved from event to event and the implementations mature as time passes. The upcoming Face2Face event in Tel-Aviv, Israel on October 8-12 will definitely show high level of interoperability as this is the 4^th event that MONA is being tested.

Taking into account all of the above, I would expect to see MONA enabled models out in the market during the second half of 2008. Some initial models might actually hit the market prior to that, and maybe, just maybe, there will be a vendor or two that make it to Christmas this year.

Technorati Tags: 3G-324M, IMTC, Interoperability, ITU, Oren Libis

Beginner’s Guide to 3G-324M MONA

By Oren Libis

MONA is a call setup time reduction technique used in 3G-324M. In the past several weeks I have noticed that a lot of handset developers and operators out there – not members of the IMTC, are a bit confused at what MONA is and how it really works.

The 3G-324M Activity Group in the IMTC is working hard in the past year on MONA. We’re doing interoperability testing whenever we can and we are going to meet again during October 8-12 for a face-to-face interoperability event with MONA as one of the main items.

What is MONA?

MONA is a call setup time reduction specification for 3G-324M. It is a set of 3 different techniques: MPC, SPC and ACP. I won’t go into the technical aspects of each, but it is important to understand the following points:

1. Each of these techniques alone can reduce call setup time to below 1 second.
2. Each of these techniques has its advantages and disadvantages – this is why MONA specifies three different techniques and not only one.

MONA Classes

3G-324M MONA specifies in addition to these 3 techniques, 3 different classes. 3G-324M products need to support only one of these classes. Each class indicates which of the 3 techniques (MPC, SPC and ACP) need to be implemented:

• Class 1, which requires MPC, SPC and ACP
• Class 2, which requires MPC and ACP
• Class 3, which requires SPC and ACP

The different MONA classes are interoperable with each other. For example, if two handsets support MONA, one supporting class 1 and the other supporting class 2, the call that will be established will either end up using MPC or ACP; if one supports class 2 and the other supports class 3, the call will simply use ACP.

What does is mean to you?

• If you are a developer, you should choose to develop the class that makes the most sense to you in terms of resources, footprint, memory and time to market.
• If you are a mobile operator, you should not force vendors to support a specific class – let your vendors choose their own class – in the end result, you will still get below 1 second of call setup time and you will be giving the vendors some flexibility.

Technorati Tags: 3G-324M, MONA, IMTC, Interoperability, Oren Libis

Interoperability in the Real World, Part 2

By Oren Libis

Last time, I tried to explain my view on the GCF test cases. As these are test cases that you need to pass before deploying your product (by going to GCF test labs), no matter how farfetched they are, you need to handle them. But there are another important interoperability issues that the GCF doesn’t handle. These are the real deployments out there today.

There are a large and growing number of 3G handsets out there and they are coming from several handset vendors. Each one has its own behavior and quirks. You’d be amazed how much effort it takes when you develop a 3G-324M stack to handle all of these quirks and how much you need to invest on the codec level and application level to get things done right.

Difference in behavior

This difference in behavior happens due to the complexity and richness of 3G-324M. Granted – it does only a video call, in a straightforward enough scenario, but the amount of options that this single scenario has is almost unlimited:

• It supports multiple types of codecs each with its own set of configurable parameters
• There are H.245 messages flowing
• Media quality needs to be handled differently by the various media systems out there
• Different developers have implemented 3G-324M, each one understanding the standard in his own way

Server side equipment

There are also servers on the network. These most of the time are using circuit switched networks in front of the handsets, where they are running 3G-324M, but they are also using IP based standards such as H.323 and SIP on the network side, when interacting with media servers for example. They have a different kind of behavior than handsets and they have a different decision making processes designed into them, bringing in more interoperability issues to bear.

What do you do?

The most important suggestion I can give developers of 3G-324M products is to do the GCF test cases that they must in order to get validated, but to focus and invest a lot on the handsets and servers interoperability. Try to get your hands on as much information as possible during your development regarding the differences in behavior of the handsets and servers and make sure you test against as many handsets as possible before you try to deploy your product through an operator.

Technorati Tags: 3G-324M, WCDMA, Interoperability, GCF, Oren Libis

Interoperability in the Real World

By Oren Libis

Managing interoperability for 3G-324M is not easy if you are a handset developer. There’s a lot to be done and some of it doesn’t always make sense.

What happens when a handset manufacturer finish developing and testing his 3G handset and wants to go sell it through an operator?

This seems like a straightforward enough process: you take the handset, you make sure you test it properly in your labs with a professional QA team and you’re done. That may be the case for things long supported by 3G handsets, such as audio calls over GSM or sending SMS messages, but for 3G-324M this is usually a bit more complex.

3G-324M testing has several different test phases: there are the IMTC, which does interoperability events – and publishes test cases, you have the GCF test labs, which validate handsets using a subset of the IMTC test cases, and then you have handsets and servers that are already deployed.

I have been working for a long time now with handset manufacturers and I have come to the conclusion that sometimes the focus is on the wrong kind of tests.

It might take a bit of time, so let me start by focusing on the GCF.

Take the GCF selected test cases for example. Since most of them are important when you validate your handset – they are all mandatory. But from analyzing them closely you can easily split them up into 3 distinct groups:

1. Important test cases
2. “Nice to have” test cases
3. Unnecessary test cases

I’ll give an example of each. By the way, as the GCF test cases are simply references to the IMTC, you can find all of these test cases here, separated into two distinct documents: interoperability and compliance.

Important test case
An example of an important test case is test case 54. It deals with master slave conflicts – a situation that is common when you have a call between two handsets from different vendors. A few years ago, a lot of handsets on the market and those developed by IMTC companies were unable to pass this test case. As this one deals with a plausible and common scenario, it is important to test it.

“Nice to have” test case
A “Nice to have” test case is test case 47. It checks to see if a handset is capable of accepting a change in media transmission rate because the other terminal/server requested him to do so. I have never quite seen this kind of a scenario happen in real life (it might, I just never saw it). You can take my word for it that this procedure is not that necessary and effective when video is presented on a small screen like the one used in 3G handsets. So this is a “nice to have” test case in my view – it’s a good enough feature, but the problem it comes to fix is just not there most of the time.

Unnecessary test case
An unnecessary test case is test case 45 (and 45u). In this test case, you need to respond to a RequestMultiplexEntry message – either by acknowledging it and sending the entry’s information or rejecting it. If someone is sending it to you, it means that he is already in a lot of trouble, as he didn’t remember what you told him (there are only 16 entries, so this must make him a senile). Let’s assume you reject it – this makes him unable to do a thing about it but drop the call. So we have a test case where the one you are working against is faulty/senile – you choose, and you can decide you don’t support this feature, hence causing a disconnection (and you are still validated by the GCF!). I have never seen a real handset acting in this kind of a way when the terminal he was working against was doing his part of the job. This means that developers need to handle this test case (and a few others similar to it) although their handsets will never actually be in this scenario.

Distinguishing between the different test cases is not easy and requires some knowledge in 3G-324M and in what different products, both handsets and server, are doing. At the IMTC’s 3G-324M Activity Group each company gets to work against a large variety of companies and products with the actual QA and development teams of these companies. This provides important information that can assist any handset vendor to pass his interoperability tests once he gets to that point.

Technorati Tags: 3G-324M, WCDMA, Interoperability, IMTC, GCF, Oren Libis

Hosting an Interoperability Event

By Oren Libis

It is now final. My company will be hosting the next face-to-face interoperability event for the 3G-324M activity group on October 8-12, 2007. It has been a bit over a year since we hosted our last event and it seems like I am getting the hang of it.

As we are planning our next event, there is this shopping list of issues that we will be taking into consideration:

• Location
  Need to find a big enough place to accommodate the group. A table for each company, with some space between them.
• 3G coverage
  We have to make sure that there is good 3G coverage in the location of the event and that it can hold a capacity of 10 or more video calls simultaneously.
• ISDN lines
  BRI and PRI. There are those that don’t have direct access to the 3G network, or those companies that would like to test their gateways, so we need to provide ISDN access as well.
• Connectivity of 3G and ISDN
  Now that there are two separate networks (3G and ISDN), we must check that you can call from one to the other and vice versa.
• Wireless LAN
  Everyone wants to use the internet during this week. Might as well provide good access to it.
• Lunch
  The army walks on his stomach and engineers can’t think without sugar. We have to make arrangements for lunch each day – in different restaurants, with English menus.
• Social event
  We’re hosting the event, so we need to give people some good time. Last year it was Jerusalem – this time it is still open. Any suggestions?

There are additional issues such as banners for the event, visa invitations, and restaurants for the evenings...

This event is definitely going to be around MONA call setup time, H.264 video codec and AMR-WB speech codec again, but I have a pretty good feeling that these should go even better than the last time for our group. I can’t wait to meet all of the guys here in Israel!

Technorati Tags: 3G-324M, Interoperability, MONA, RADVISION, Oren Libis

Are Open Standards helpful and beneficial?

By Anatoli Levine

Open standards play a vital role in today’s communications. Traditional PSTN telephony, which is still empowering most of the world to communicate, wired and wireless IP networks, Internet, World Wide Web – all of this technologies we are so used to are based on Open Standards.

At the same time, open standards have their own “dark” side. They require heavy investment of time and money to develop – top notch experts from all over the world spend lots of time working on the standards. Once developed, implementation and deployment are also costly, as interoperability needs to be tested and verified. Additionally, the need to “play by the [open standard] rules” might adversely impact time to market.

A lot of today’s success stories, as Skype, for instance, are closed end systems. You don’t spend lots of time trying to reach consensus in ego and politics fight, you deploy when you ready, you control who connects to your network, you change implementation as you see fit – and this list of advantages can be easily continued.

So in the end of the day, are Open Standards helpful and beneficial or not? Do they push technology forward or become a stumbling block? IMTC (International Multimedia Telecommunications Consortium), together with PulverMedia, assembled panel of experts who will help us to find answers to some of these questions.

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!