Q&A: SIP pioneer/Cisco Fellow jumps ship to Skype

Jonathan Rosenberg, co-author of the Session Initiation Protocol, joined Skype in November 2009 as chief technology strategist to apply what he's learned about disruptive IP technologies. Network World Editor in Chief John Dix caught up with Rosenberg over a Skype voice connection to see what the Skype lure was for him.

Jonathan Rosenberg, co-author of the Session Initiation Protocol, joined Skype in November 2009 as chief technology strategist to apply what he's learned about disruptive IP technologies. He's learned a lot. He began working on IP communications in 1996 at Bell Laboratories, and left there in 1999 to join start-up Dynamicsoft as CTO working on service provider VoIP. Cisco acquired that company in 2004 and Rosenberg stayed there for five years working on both service provider and enterprise VoIP, ultimately becoming a Cisco Fellow. Besides SIP, Rosenberg was inventor of SIMPLE - SIP for presence and IM, and is the principal author of multiple VoIP firewall and NAT transversal technologies. Network World Editor in Chief John Dix caught up with Rosenberg over a Skype voice connection to see what the Skype lure was for him.

What do you do at Skype?

My role is to direct our high-level system-level architectures across our products and work on our technology strategies and figure out what areas of investment we make, which technologies we bet on. That is a pretty broad mandate, especially for one guy, so I tend to focus on particular areas in projects. Much of my work has been focused in two areas, the Web and Skype For Business.

Speaking of architecture, can you give us a thumbnail of the Skype architecture at this point? Has it evolved much?

Wow, that is a big question. As with any technology that has added new products, Skype has seen a lot of change over the years. We've added mobile, we've invested in business via the Skype for SIP product and we've invested in video calling features, all of which have had an impact on our architecture. But we remain a peer-to-peer service for many of our core features and functionality and that works in concert with back-end services and infrastructure that support many of our paid products. So we are a hybrid technology today.

Still no Skype backbone to speak of, right?

We don't have a dedicated IP network.

Every time I log onto Skype I see there are X million number of people online, but what does the Skype customer universe look like?

We have approximately 560 million registered users and we have online simultaneously around 23 million users at a time, which is something we're proud of. In terms of minutes, we've done about 250 billion worth of minutes of Skype-to-Skype calls since we started and now account for 12% of all international calls -- not voice over IP international calls, all international calls worldwide -- a growth of 50% year-over-year compared to 2009. So that is huge. We are preloaded on eight out of 10 PC's. And in terms of financials we exited 2009 with about $716 million in revenues, which is 30% annualized growth.

Of that international traffic, is that mostly voice calling or a combination of voice and video?

Glad you asked. Very much a combination of voice and video. Approximately 36% of all our Skype-to-Skype calls include video and that is a number that peaks at over 50% on holidays like Mother's Day. In fact, if you multiply those numbers together -- we represent 12% of international traffic and 36% of that is video -- it means 4% of the world's international long distance traffic is now video based and that is an astounding number given it was effectively nonexistent just a couple years ago.

But in terms of our user base, it is everybody. We have consumers to small businesses to large enterprise all over the place. There is no one user base and the same is true from a geographic perspective. We are a worldwide brand and we have people using us for personal and business usage all over the world.

Let's turn to the business stuff, that part of your job. I watched videos on your Web site about how companies such as Rip Curl (a surfing company with thousands of employees) and Maxim (a $1.5 billion manufacturer) use Skype, and frankly I was surprised companies this large are using you so heavily.

In larger companies it's not necessarily the case that everyone is using Skype, but because people can just go grab it, groups of users are adopting it. Particularly when work forces are distributed, when you have people at home, telecommuters or others that work outside of an office, it is just a fabulous tool for keeping in touch with colleagues. And from a business perspective IP completely wins because it is low cost, it works wherever those users are and there is almost no operational cost for maintenance and management. The basic services are free so it is a huge win. It isn't limited to small business; it's everybody from the largest enterprises to the tiniest company. People need to work wherever they are and Skype is really great for that.

Is it typically brought in as a complement to an existing phone system?

It's a mix of stuff. You saw on some of the video use cases it's a pure replacement if they don't have a phone system. Our company is an example of that. We don't have a phone system at all; we use Skype. But for a lot of people I would say it is an addition and it, again, facilitates distributed work forces where I am not bringing my desk phone with me or I'm on the road or I am in a virtual office and we don't have desk phones or a PBX in that office. I think it often gets used in concert with mobile phones, so if you have Skype and a mobile device you don't necessarily need anything else.

Is there a typical business use case for your services?

I don't think there is one. Depending on the company, there are different benefits. For some people it's about being mobile. For others it's about cost and being able to save money on outbound calls, in which you don't need to buy or pay for a separate phone system. For others it's about video and the ability to have that extra level of interaction between users, and that's really powerful. For others it's about connecting to the Skype community. So it's all these different things for different people.

For a company that is looking at Skype as a primary telecommunications service, do you give them a general sense of metrics like call quality or call completion, or do people acknowledge that it's just best effort and roll with it?

It's best effort and people roll with it and, you know, they get enough value out of that that it's worth it. Anyone who depends on a mobile phone for businesses can have a system problem and there are no guarantees and it is similar in our case, in particular …

Are you still there? [Skype call goes dead for 2 to 4 seconds, but then returns.] Speaking about best effort, ironically we lost you for a minute Jonathan.

Sorry about that. So, I was saying exactly that point. We can't make any promises about the quality of the access links or the availability of bandwidth or problems on the Internet, and people, sort of, roll with it. Skype spent a huge amount of intellectual capital on doing the best job we can under a variety of pretty harsh conditions and we're always getting better at that.

And we're doing more and more to help businesses. For example, we are in the process of putting together a Skype for Business management guide that helps you figure out how to make sure that there is enough bandwidth and set up your network properly. We also just recently added tools right there in the client to help let users know about what the quality levels are and what they can expect for a call. It is a combination not just of Internet bandwidth but things like, do you have a microphone and headset plugged in and is it working. So we look for all that and we give them indicators about what to expect.

So in the case of your company where you are using it internally for the whole organization, I presume desk-to-desk calls don't bounce out to the Internet? You're routing calls internally in some fashion?

Yes. Skype will do what it does best, which is connect the calls in the best path possible. So if you and I happen to be sitting together in the same corporate office and we call each other, that media in most cases is just going to travel between our computers. We are not going to necessarily go over the Internet. That happens in general with Skype and it happens when you use it within the same business. Of course if people are in two different corporate offices, it will go over the Internet connectivity that we have between the offices.

There is no Skype server sitting in the company?

No. Skype-to-Skype calls are peer-to-peer. What is the meaning of a corporate wall, anyway? I mean, we have people all over the place, right? We have some people working in airports, some working from home, some people in offices, and some people in Internet cafes. The notion of a corporate wall where you are in a building and at work and not in a building and not at work, that model doesn't work anymore. This is why we are seeing so much success with Skype because it is built on a model that says you just connected to the Internet and wherever you are, you are able to communicate with whomever you want to talk to. That is a model that works much better in the modern mobile workforce and the environment that we are in today.

When Skype first emerged there was concern about the peer-to-peer architecture sapping corporate resources. If I became a Skype business customer, would some of my infrastructure end up supporting voice traffic from other customers?

So this is the question of supernodes and media relaying and things of that sort. The answer is in most cases no. It is true that Skype remains peer-to-peer and we leverage a network of nodes in order to facilitate communications between end points. However, in the vast, vast majority of cases, your own computer is being used to make your own calls. For a very small number of users -- in particular ones that have open Internet access and their machines are not behind a firewall or a NAT and they have a high amount of CPU -- we use a relatively small amount of the resources on the machine to facilitate call setups to other computers, and we are very careful about controlling that.

In fact, even when we use those machines to facilitate audio and video, we are careful to control the bandwidth. It's only a small fraction of what the user has available so won't interrupt the experience of the user. But to make the point again, the only way you become one of these supernodes is if you have public Internet access and you are not behind a firewall NAT. The vast majority of computers don't apply and, in particular, almost every machine that sits inside a business is behind a corporate firewall and they will never get elected to be a supernode.Tell us about Skype Manager, a tool aimed at business customers.

Skype Manager is a set of tools that help an IT manager manage the use of Skype within their network. It allows them to provision users, to allocate credit, to see how much money users are spending. It allows them to control features for the way the client works. It even gives them call detail records. So when you make a Skype Out call that generates a call detail record and those records are visible from within Skype Manager so you can get a sense of what your users are doing and who they are calling and how much money they are spending.

How about this Skype for SIP open beta? As I understand it if you have an IP PBX you can use Skype for SIP and use Skype as the transport?

That's exactly right. It has been a very popular service. In fact when we announced the closed beta we had, I think, around 10,000 applicants to give you a sense of the scope of interest. What it effectively does is extends an SIP trunk to the PBX and allows outbound calling worldwide in the same way our Skype Out allows out bound calling worldwide at great rates. That now gets extended to the enterprise through their PBX and it also allows companies to receive inbound calls, to publish Skype IDs out there on the Web so someone with a Skype client can call into through the company PBX via Skype and it rings a phone on a desktop. That's really powerful and it's something that is much different from what you would see from a traditional SIP trunk service provider. This is not just about long-distance rates. It's about connectivity to the Skype user base and that is an incredibly powerful asset.

How are you making money on the business services? Where is that $716 million in revenue coming from?

Our revenue comes from a bunch of places. Of course, much of it is from our consumer users and there we have always offered several paid products. Skype Out [which lets you use Skype to dial regular phones and cell numbers] product is by far our most popular paid product. We also have other paid products such as SMS. We've recently announced a group video calling feature that for now is free as a trial but we will be charging for but we haven't announced pricing.

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