April 28, 2006

Tone Deaf VoIP

Beginning of this week, there were reports that Skype has reached an agreement with EMI to sell music. Indeed some even suggested that Skype will be a worthy competitor to Apple’s iTunes business. After a couple of days of such speculative analysis, the official word came out: the partnership will not be selling full length tracks, but just ring-tone downloads. Oh what a disappointment – not because Skype will not be retailing full tracks.

On the lighter side, it is disappointing because the blogosphere missed an opportunity to spin a yarn about how the founders can now smooth over their riff with the music industry and that they can personally attend trade shows in US. Oh well.

More seriously now, it is disappointing that many who otherwise advocate and celebrate “intelligence at the end” do not see the irony of ring-tones costing 20% more than the full track. After all, iTune charges about $1, but Skype charges $1.20 for a ring-tone. “Intelligence at the end” suggests that one must be able to use any sound file available at the end as a ring-tone. In other words, $1 iTune can be used as a ring-tone. So why pay extra? I say that for “intelligence at the end” to work beneficially, the “End” has to be intelligent.

There is another rage in the mobile phone industry that goes by the name ringback-tone. To subscribe to this service, a mobile user pays a monthly fee so that callers to this subscriber can hear pre-selected tune instead of the standard ringback tone. I am expecting that this service will jump to VoIP service as well. After all VoIP just mimics PSTN.

Posted by aswath at 07:40 AM | Comments (0)

April 20, 2006

Skype is not detectable. Really?

Russell Shaw has located an analysis by Art Reisman, CTO of APconnections, maker of packet shapers. Apparently, Reisman was asked to see whether an external party can detect and if so then block Skype traffic. The background discussion is long, but the real analysis is short. It seems none of the tricks the author uses to identify a voice flow worked. So, the author surrenders and hopes others will solve the mystery. It is so disappointing. The author could have at least commented, if not studied, the scheme used by Verso. If you recall they have claimed that they can successfully block Skype traffic, that some service provider in China is trialing their product and the product has been verified by an independent agency. Either the author is correct and Verso’s claim is not valid or the author’s research methodology needs to revised. Unfortunately, we do not know. I also feel that the author is amiss in not referencing prior works that have managed to identify Skype traffic. So here again we do not know whether such identification is enough to block Skype traffic. All in all, this is not an informative analysis.

Posted by aswath at 04:42 PM | Comments (2)

April 19, 2006

How COULD Skype support CALEA?

It has been widely assumed that because Skype encodes the speech, it is not easy for the governments to intercept a call for monitoring purposes. Today, Financial Times reports that Skype CEO agreed that Skype filters certain texts from chat session in China (if only indirectly through their partner Tom Online). Indeed, the CEO is quoted as saying: “I may like or not like the laws and regulations to operate businesses in the UK or Germany or the US, but if I do business there I choose to comply with those laws and regulations.” But we do not know the full scope the filtering. This raises the possibility (for many a surprising one, I am certain) that Skype may agree to assist in the legal intercept of a voice session. Mind you, I am not suggesting that they have agreed or that they have facilitated this. But I am interested in knowing how they could go about implement this capability IF they were approached AND IF they agree to cooperate. I am using US CALEA regulations as an example.

CALEA has two aspects: the first one is interception of call control information and the other is interception of call content. The legal requirements are different. Nonetheless, a LEA has to get approval from a legal authority and produce the order to the relevant service provider. In this case Skype is advised ahead of time the identity of the target. We also know that when a user logs into Skype system, the user is given a list of supernodes to try. We do not know on what basis, Skype selects this list. But Skype can clearly select its set of supernodes (let me call them CALEA supernodes) and deliver only that list to the target. This way, Skype can ensure that only CALEA supernodes will serve the target. Then it is a simple matter for the supernode to collect call control information and deliver to the relevant LEA(s).

If the LEA is authorized to intercept call content as well, then the CALEA supernode can be instructed to use a relay supernode (again operated by Skype for the purpose of CALEA) and use the relay supernode to intercept the call content. The fact that the content is encrypted is not a big problem, because Skype can deliver the key to the LEA through CALEA supernode.

Of course, I have omitted certain difficult aspects of CALEA; but then any VoIP system will have those difficulties. My point is that, once Skype is willing to abide by a country’s laws they can easily provide support for CALEA as well, all within their current architecture. One thing is clear: claims not withstanding, geographic boundaries do exist in Internet. It better be; otherwise one can not hope to offer location based services.

Posted by aswath at 04:57 PM | Comments (2)

April 18, 2006

ISO Reference Model - ISORM (as in eyesore)

Recently Ken Camp posted a great overview of ISO Reference Model for Open Systems Interconnect. In this post, I would like to share my understanding of and my thoughts on ISO RM. Many of the points I make here are based on my readings of RFCs by M. A. Padlipsky from early days of “Catenet”. By the way, if you not done so, you will do good by reading him. He is very acerbic and you may find it to difficult but it is worth the effort. Any student of end-to-end argument must do so. By the way I will use Ken’s summary, even though I don’t mean to pick on his writing; it will be easy to refer.

The Internet model and ISO RM couldn’t be any more different. It is ironic that many try to force fit Internet into ISO RM as if it is required for its legitimacy. In fact it should be other way around. Internet has demonstrated that ISO RM has to be changed and changed so drastically, that it shouldn’t be called ISO RM.

Let me start with the Data Link Layer. ISO RM and its realization X.25 did not anticipate multiple access technologies. Both of them visualized only point-to-point links. So MAC protocols like CSMA/CD have no place in ISO RM (not withstanding Ken’s suggestion and the entry in Wikipedia; if you don’t believe me, take a look at the standards). When ISDN Basic Access introduced “passive bus” as the multiple access technology, ITU added it to the physical layer and not LAPD, the link layer.

In my opinion, another significant implication of this assumption is that multiplexing of different flows didn’t take place at the Link Layer. Indeed, when the proponents of Frame Relay encountered cultural opposition because their proposal took advantage of multiplexing at the Link Layer.

For a long time, ISO RM subscribed to link-by-link error correction and not end-to-end. There is a famous paper by Kleinrock where he argues the advantages of the latter. In my opinion three things influenced ISO to change its RM: inherent error-free nature of modern communication systems, success of Internet and Frame Relay. In this respect, ISO RM missed in anticipating an important design principle that has simplified Internet.

Yes, it is beneficial to have a Reference Model. But what is the benefit of maintaining a failed model? Aren’t we better off it assuming the Internet Model?

Posted by aswath at 08:01 AM | Comments (0)

April 13, 2006

Post-Disaster Communications Petition

Recently, FCC placed on public review a petition filed by Evslin Consulting and pulver.com. The petition grew out of the experiences felt during a breakdown in communications network caused by Hurricane Katrina. As you may recall, whole communities were evacuated in the Gulf coast and many families were separated because they ended in different cities. Added to the trauma, many of these evacuees found it difficult to contact and communicate with each other. But those who have VoIP service and those who subscribe to premium features on their PSTN lines were better off because their services were able to forward the calls to the new location. The petition further notes that low income people were affected disproportionately during this period. The petition suggests ways to handle such disasters in the future and requests FCC to adopt their suggestions.

Evslin and pulver feel that most of the affected would have been satisfied to exchange information about their whereabouts and their safety. After all that is exactly what they tried to do via multitude of helter-skelter volunteer locator boards. Accordingly they suggest that when an area is generally affected or evacuated, then the local service providers must automatically terminate the calls to ALL of their customers, in a voice mail system. This will give a dependable place for people to leave and retrieve messages.

They go on to suggest that FCC require of those service providers who do not offer this emergency voice mail service to immediately port the affected customers’ numbers to an alternate service provider selected by individual subscribers, with the geographical limitations imposed by the prevailing LNP ruling. I don’t think this is a punitive requirement because the porting could be revoked once the emergency has cleared.

These two suggestions taken together are beneficial for the society at large; state clearly when it could be invoked and the effective period; do not adversely impact any business prospects for the service providers. For these reasons, the petition should receive wide support and all of us should urge FCC to consider it favorably.

The petition grants via a footnote that setting up such a voice mail system may involve capital expenditures and also require extensive logistics. They suggest that these expenses could be subsidized by Universal Service Fund or other funding sources. I am of the opinion that this expense will be small and can be spread to multiple willing contributors. The anticipated storage requirement can be offset if the voice mail system converts the voice mail into an email, instead of storing it in the voice mail server. The advantage is that the email server could be hosted by the service provider itself or could be hosted by a willing third party. Since many email providers operate on the assumption that storage is effectively free, there will be multiple volunteers during an emergency. Even the PIN management can be handled efficiently. For example, Red Cross can b given free access to such email servers from designated computers and its volunteers can assign PINs to affected public as and when needed. So I urge you not to consider the cost or logistical difficulties – they can be effectively contained, if not mitigated.

I have one final observation. Given the background of the individuals behind this proposal – Tom Evslin and Jeff Pulver - it is possible that some may construe this petition to favor IP Communications industry. I submit that it is indeed the other way. For a long time, people have expected VoIP technology to eclipse PSTN. But at least till now, the market place seems to suggest that they are at par. This petition dilutes, if not totally eliminate the inherent advantage IP networks have during a disaster.

You can get more information from Jeff and Tom and also the full text of the filing. If you are interested in adding your voice to this topic, you can add your comments by visiting FCC’s site. Please keep in mind that the petition reference number is RM-11327.

Posted by aswath at 06:24 PM | Comments (0)

April 10, 2006

How will Skype React to Pressure from Big Brother?

Kevin Delaney recently wrote why Skype is still better than Yahoo Voice. That it very well might be. But one of the reasons he stated was that “[Skype] are fully P2P and encrypted. Nobody's listening, while Yahoo will submit under the pressure of big brother to eavesdrop.” I remember reading somewhere that Skype had indicated that they will cooperate with appropriate legal authorities. Phil, in his followup comment asked for a specific reference. Apparently my reply was blocked (it is a regular occurrence for me in Skype Journal; indeed I was surprised that my first comment made it). So Phil, here is the reference you asked for:

"Kurt Sauer, Skype's chief security officer, said there are no "back doors" that could let a government bypass the encryption on a call. At the same time, he said Skype "cooperates fully with all lawful requests from relevant authorities." He would not give particulars on the type of support provided."

By the way Kevin, I am not sure whether your comment "Never heard of that" refers to my comment or not. In case it does, I hope this link interests you.

Posted by aswath at 09:04 PM | Comments (0)

April 09, 2006

Masquerading VoIP

These days lots of services get the “VoIP” label. It is one thing that ATA-based services are called VoIP, but calling the new offering from Jajah to be VoIP is over the top. To place a call, users will visit their web site and provide theirs and the other party’s phone numbers; then Jajah will place calls to the two numbers and will bridge the two calls. It is very likely that Jajah originates the calls over IP. But that shouldn’t be sufficient to say that this is VoIP. Neither of the users derives any benefit and the users’ experience no different than if Jajah had placed the calls over PSTN. Isn’t it time that we place a stricter and narrower definition for VoIP?

Posted by aswath at 11:11 PM | Comments (3)

April 08, 2006

Excuse for a Party

A couple of days back, Jeff noted: We just passed 01:02:03 on 04/05/06, a pretty rare numerological event in the "Common Era." He went on to invite us to an inspired party on 12:34:56 on 07/08/09. Not being a party animal, I would rather have that early rather than later. Since, the VON crowd is truly global and the fact that many use dd/mm/yy notation, we should plan the party on May 4 th of this year. Further I suggest that in keeping with the global perspective, the party should start at that rare time in the International date line (+) area and end at that time in the International date line (-) area.

Probably Jeff can facilitate a virtual party, where we can get together in the party room and “chat”. Of course, the background music will be representing the area which is going through the rare time (in case people don’t want to listen to Herding Cats for the whole day :-) ).

Posted by aswath at 12:16 PM | Comments (0)

April 02, 2006

Did You Get My April Fool’s Joke?

I am sure you read all the intriguing press releases yesterday and most likely were not taken by it. If you visited this site to read my version and thought I didn’t foll you, I just wanted to let you know that I had the last laugh.

Emile: So, you expected me to fool you, didn’t you?
Raymond: Yes.
Emile: But I didn’t, did I?
Raymond: No.
Emile: But you expected me to, didn’t you?
Raymond: Yes.
Emile: So I fooled you, didn’t I?

(From “What is the name of this book?” by Raymond Smullyan)

Posted by aswath at 08:13 AM | Comments (0)

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