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Mobile Skype: Quality Issues?

VOIP peer-to-peer pioneer Skype on Tuesday made a big move by porting its popular desktop VOIP client to certain wireless handhelds. Sounds neat, but now that the news has digested, the big question appears to be: Will it really be worth it?

Skype's introduced a PDA version that will work with 802.11b-enabled Pocket PC handhelds with more than 40 Mbytes of memory onboard (see Skype Me? Skype You! on the regular Skype client).

In theory, this is an application that enables users to -- at least partially -- bypass wireless carriers: If users live in an area with plentiful WiFi hotspot access and all their friends and family use Skype.

That's a big if, if you consider the nature of hotspot coverage when compared with traditional mobile networks: It's spotty, at best...

How spotty? Get all the details on Unstrung.

— Dan Jones, Site Editor, Unstrung

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stephenpcooke 12/5/2012 | 2:05:15 AM
re: Mobile Skype: Quality Issues? Also, at what point does a circuit get set up on the class 5? How many messages does this require and what is stopping them from overloading that class 5? Thanks.
dljvjbsl 12/5/2012 | 2:05:13 AM
re: Mobile Skype: Quality Issues?
'next to no resource on the proxy'


SIP does not maintain state for calls though the proxy. No memory is consumed and so it is not possible for the SIP proxy to run out of resources in trying to service multiple call attempts.

Trust realtionships can also be set up so that the proxy will ignore messages from unknow sources.

This issue has been adressed by the 'in-crowd' who control the SIP standards.
stephenpcooke 12/5/2012 | 2:05:12 AM
re: Mobile Skype: Quality Issues? SIP does not maintain state for calls though the proxy. No memory is consumed and so it is not possible for the SIP proxy to run out of resources in trying to service multiple call attempts.

How does this relate to class 5 circuits?
stephenpcooke 12/5/2012 | 2:05:12 AM
re: Mobile Skype: Quality Issues? dljvjbsl wrote:

I should ahve mentioned that the availablity requirements for telpehone networks are much more subtle thanhte 5 9s that is always mentioned. However even with that there are vunerabiliites in the network for major outages. The SS7 overload message bug which shut down the network in the eastern US several years ago is an example of this. I know of no similar occurence in the Internet.

Even DDOS attacks target only single locaions and can be defeated by modifying the routing in the core. Single bugs do not seem to be able to shut down the network as has happened in the PSTN


I may be one of the few who understands the availability requirements in NEBS better than most. The test company that I worked for was a NEBs house and was Verizon certified. I was also the troubleshooter of last resort on Nortel's TransportNode product line and have some experience with network outages. The troubling part about your comment for me is that the outage that you describe was not a 'known and widely published' difficulty prior to the event. Yes, there are vulnerabilities in the PSTN but they are extremely difficult to find and it is even more difficult to make purposeful use of them on a large scale. Just because you know of no DDOS attacks that have gone after more than one location does not mean that there haven't been any or cannot be any in the future. SIP interfaces to class 5's are not 'generally unknown or unpublished' PSTN vulnerabilities, these are widely published standards available to everyone with Internet access. Also, someone who REALLY wanted to could quite conceivably go after many different bugs all at once, just because they are there and published freely. Of course it helps that they can write their own interface to a class 5 and distribute it via the Internet incredibly easily and they can have a whole bunch of computers do the damage for them.
aswath 12/5/2012 | 2:05:10 AM
re: Mobile Skype: Quality Issues? stephenpcooke:

I do not see the problem for the following reasons:

A VoIP call can interconnect to the PSTN through a gateway. Whether this gateway is owned by a carrier or not, it is a line termination (phone), trunk termination (PBX) or a switch termination. So the PSTN network will use the standard protection mechanisms that are in place to handle overload. If the concern is that with VoIP, calls can be generated without a human intervention, isn't the situation similar to have a virus program in a computer that is designed to generate modem calls?

What am I missing?

Aswath
stephenpcooke 12/5/2012 | 2:05:08 AM
re: Mobile Skype: Quality Issues? Aswath, your understanding and mine are somewhat similar in this except that, to generate modem calls you have to have multiple physical phone lines and physical modems connected to them to overload a switch. With an IP service you can have a single connection from multiple 'zombie' computers that can each generate multiple call requests, no real 'physical barrier' exists anymore.
technonerd 12/5/2012 | 2:05:07 AM
re: Mobile Skype: Quality Issues? However WiFi can accomplish much more than voice and much more than the cellular network is capable of.
This is the usual chatter of the propellerheads and propellerhead wannabes. It is based on very shallow thinking about "Wi-Fi" that's very reminiscent of equally shallow thinking about "DSL" that led to the loss of tens of billions of dollars during the Bubble frauds.

Like DSL, Wi-Fi is a marketing term. Wi-Fi has come to stand for anything operating over one of several 802.11 wireless standards. The key attributes of these standards are:

1) Unlicensed frequency
2) Broadband capable
3) Very high frequencies
4) No cell handoffs

At the moment, posters here focus on #2 but what matters most are #1 and #3 and #4. Wi-Fi being unlicensed means that its ability to be used for a high-volume commercial service is limited. In the incredibly unlikely event that a Wi-Fi carrier ever really did damage to a cellular carrier, the cellular carrier could force it to sell out by threatening to interfere. Nothing in the law could stop it.

But #3 is by far the most crucial weakness. Wi-Fi works on microwave frequencies with limited propogation. To compete effectively with cellular you'd need comprehensive coverage, and to do that with Wi-Fi you'd need many millions of cells. Each of these cells would have to be a base station connected to the Internet. It would be incredibly expensive for any carrier to blanket the country with Wi-Fi.

Problem #4 is also a voice killer. Wi-Fi doesn't allow for handoffs, which means it can only be portable rather than mobile. What does someone do with their Wi-Fi phone in their car? Nothing. It won't work in their car, because the car is moving and you can't do handoffs. Not only that, but if they ever did develop handoff capability could you just imagine the difficulty of managing the number of handoffs involved in a typical mobile session given the small sizes of cells?

Why am I reminded of DSL here? Because when CLECs were installing DSL (or claiming to), neither they nor the propellerheads in places like [i]Light Reading[/i] and the other trade journals ever bothered to look at the details. If they had done so, they'd have used different line codes. If outsiders had ever bothered to look, they'd have realized that the CLECs were making a fatal mistake when they used 2B1Q instead of QAM.

But that level of diligence required, well, diligence. And for VC-backed trade journals it required a level of integrity that they did not have, do not have, and will not have. If some VCs ever climb on the 802.11 voice bandwagon in a serious way and some IPOs loom, I have no doubt that Wall Street and the trade rags will do exactly what they did in the late '90s with respect to DSL: Spread any lie they can get away with, regardless of how outrageous.


To my mind
... such as it is ...


the failure of the 3G network is not purely technological but is instead more of a reflection of the inability of telecom-type networks to supply services fitted to the needs of particular users. 3G does what it does but it is too little compared to what can be done with other technology.
More ignorance talking here. 3G is another marketing term. It refers to wideband services delivered on sub-microwave high frequencies. The technology works fine, but it's expensive. Especially if you put it on the upper band of cellular, which turns out to be the lower end of microwave but not quite microwave, i.e., what was once called the "PCS" frequencies.

Put 3G there, and you need four times as many cells to get the same coverage as you do with the 800 HMz frequencies. But you pretty much have to use the higher frequencies for 3G, because you need all the spectrum you can get. Which means a lot of cells. Very densely packed areas can support 3G because they have lots of cell sites anyway, i.e., South Korea and Japan.

Less dense areas, much of Europe and all of the United States, have a hard time with 3G because of this issue. It's not the technology, it's the cost. You need more cellsites for 3G -- a lot more -- and that means you require paying customers for those services. A lot of them. There just aren't enough people in the U.S. who care about mobile or even portable wideband and broadband services to pay for the expansion of the 3G-capable network.

The Wi-Fi phemonenon, i.e., using microwave frequencies instead of sub-microwave frequencies for wideband and broadband packet service, is a tiny phenomenon of appeal almost exclusively to a handful of geeks. To the extent that, say, traveling businessmen might want to use such a service, the cellular carriers are going into the airports and similar locations where those laptops can be served.

And frankly, using the 3G cellular network (when available) is a lot more convenient than using Wi-Fi. Not because of any technology difference, but because logon and registration procedures are a whole lot easier. This begs the question of why anyone bothers with public Wi-Fi, and that leads back to it being something by propellerhead for propellerheads. Public Wi-Fi was funded right at the peak of the bubble by a handful of VCs in the blindest of their blindness.

Public Wi-Fi loses money, and will always lose money. The only question is when the plug will be pulled. Propellerheads who keep throwing money at Wi-Fi services really ought to ask themselves if there aren't some more deserving charities out there.
aswath 12/5/2012 | 2:05:07 AM
re: Mobile Skype: Quality Issues? Aren't the gateways the physical barrier?

For modem calls, I was thinking of multiple infected computers, along the lines of DDoS.
technonerd 12/5/2012 | 2:05:06 AM
re: Mobile Skype: Quality Issues? With an IP service you can have a single connection from multiple 'zombie' computers that can each generate multiple call requests, no real 'physical barrier' exists anymore.

I read the original post and all the replies in this thread, and rather than replying one by one I thought I'd jump in here. Stephen, you raise an outstanding point, and one that there is currently no answer for.

All you can really do is run your VoIP service through a computer hooked up to a good firewall, using an ISP that aggressively screens out spam. Even then, some of it will get through. Perhaps if VoIP ever becomes real in the consumer space, there'll be an expansion of the federal "do not call" list to VoIP.

In the meantime, anyone using VoIP will be a propellerhead science project. Which is one more of the many reasons to be a late adopter of this particular, um, "service."
technonerd 12/5/2012 | 2:05:06 AM
re: Mobile Skype: Quality Issues? You gotta be joking. Blackberry is the road warrior tool of choice. I hate the stinkin' things but they're being used by executives who make Dilbert's Boss look like a rocket scientist. Just what I need... inane email from some senior VP at 2AM.

That's funny, and trust me I do know what you mean. I remember getting a Blackberry. I eagerly hooked it up, thinking wow is this cool. Three weeks later I disconnected it because the f'ing thing drove me crazy.

Whenever I left the office, I put an autoreply on my e-mail saying that I had disconnected my Blackberry. I would check my e-mail once a day from my hotel, and if anyone needed to reach me urgently they should just call my office because it would forward to my cellphone regardless of where in the world I was.

It worked beautifully. Once I retired and they wanted me to return my Blackberry I went searching for it and found it on a shelf at home with a coating of dust. I wrapped it carefully, dust and all, and sent it back to the IT people. When they got it, they called me and said they wished there had been more people like me in the company.

More seriously, yes I know that Blackberries are used by a cohort of anal-retentive business people. They are real productivity destroyers. But in any case, by comparison to the number of cellular subscribers it's a tiny number of people who are using these things. Virtually no one pays for a Blackberry themselves. It's always a company-provided device.
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