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

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