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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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alchemy 12/5/2012 | 2:05:23 AM
re: Mobile Skype: Quality Issues? dreamer101 writes:
1) Skype use Voice codec from Global IP sound that supposed to be able to tolerate 30% packet loss with no loss in voice quality. I do nto know whether it is true

iLBC is a very good compression codec but the voice quality does drop off significantly if you have sustained packet loss. For those who aren't familiar, the iLBC codec from Global IP Sound supports basic frame sizes of 20 and 30 mSec. It's toll quality at relatively low complexity compared to, say, G.728. It's quite good at dealing with dropped packets.

Given that Wifi, DSL, Cable Modem has a lot more bandwidths than it is required for voice. Waste bandwidth so it can works in a low quality transport situation looks more reasonable that required QOS in all networks. Bandwidth is cheap in those scenerio

For voice over cable service offered by the MSOs, they're going to eventually phase in compression codecs. Bandwidth is cheap until you do the analysis on running multiple simultaneous G.711 VoIP streams on a single DOCSIS upstream frequency. DOCSIS has big pipes on the downstream and small pipes on the upstream. DOCSIS 2.0 repairs this somewhat but there's no DOCSIS 2.0 plant deployed yet and cable modems are mostly at DOCSIS 1.0 and 1.1.

The 'bandwidth is cheap' argument works great on a PowerPoint slide deck but when you do the real traffic analysis on the access network, VoIP ends up being a real hog if you have 30% market penetration on homes passed and are traffic engineering using traditional telco erlang numbers. You end up having to double your DOCSIS cable modem plant if you assume a 10% take rate on cable modem and 30% take rate on telephony. 2x the number of fiber nodes. Twice the fiber. 2x the number of CMTSs. Truck rolls to partition the network and move amplifiers around.
alchemy 12/5/2012 | 2:05:23 AM
re: Mobile Skype: Quality Issues? technonerd writes:
By the way, RIMM and Treo are gearhead toys. Very few people use them.

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.
dljvjbsl 12/5/2012 | 2:05:23 AM
re: Mobile Skype: Quality Issues?
The problem with WiFi (IMHO) remains in the business model: to date, nobody has figured out how to be successful deploying a commercial WiFi network of any breadth


It si now being offered as a complimentary service in hotels jsut as the hotels offer cable television and local phone service. These services were charged for at the beginning as well. I would expect that WiFi will be seen as a necessary amenity like street furniture in business areas and supplied accordingly
dogmeat 12/5/2012 | 2:05:21 AM
re: Mobile Skype: Quality Issues? VoIP capable AP infrastructure.

Take a look a Meru Networks. They are the only ones in this space that appear to have solved the RF problems in 802.11.
optical_man 12/5/2012 | 2:05:20 AM
re: Mobile Skype: Quality Issues? What is stopping some organized hackers from creating a network of 'zombie' computers (via worms, adware, spyware, etc.) to perform DDoS or similar attacks on our phone system?


SC,
Not much is stopping this right now. Some pretty bright minds see this as a business opp and are creating apps/hardware to secure voip networks. they will make some nice $$.
I think (however economically disruptive it is) it will be a hilarious situation when all the nations phones (or at least the max # of provisioned circuits within each switch) start ringing ALL AT ONCE!!
Funny for maybe 2 minutes, then we'll realize this is a huge wake up call, and the developers of voip security apps/hardware will FINALLY see PO's pour in by the thousands.
stephenpcooke 12/5/2012 | 2:05:20 AM
re: Mobile Skype: Quality Issues? Hi,

I have a firewall installed on my home Internet connection. I occasionally look at the logs. The firewall that I have is installed on an older Windows 98 machine (recycling, awesome!!!) so it has lots of disk space to store previous log files. I had a look at a few of those log files. On average, there were over 1000 illegal login attempts on my home network in every approximately 2-3 hours. That averages out to about one illegal login attempt every 6 seconds!!! My firewall also has a feature where I can do a whois on the offending IP address. This basically finds the ISP on whose network the offending machine resides and in some cases provides an 'abuse' contact email, but almost always gives me the country of the offending machine. Note that this does not count 'Adware' or 'spyware' programs that are unwittingly downloaded.

I had illegal login attempts from the Netherlands, Florida, Montevideo, Columbia, Australia, China, and (mostly) from within my own ISP's network. I only checked a few of the addresses.

So, my question goes like this to all VoIP advocates out there:

Given that:
- the approach is to make a dumb network (so that the network has little or no intrinsic intelligence to police the bits travelling through it)
- any VoIP network uses applications on the edge of the network (ie: resident within my computer or VoIP phone, etc.)
- most of those illegal connection attempts will have come from 'zombie' computers infected with Internet worms
- any VoIP network is not isolated because the interface to it is on the public Internet through an ISP
- there exists many ways in which I can make a phone call to someone on the POTS network through my computer over the public Internet (ie: IP to Class 5 gateways exist all over the place)

What is stopping some organized hackers from creating a network of 'zombie' computers (via worms, adware, spyware, etc.) to perform DDoS or similar attacks on our phone system?

Please explain.
dljvjbsl 12/5/2012 | 2:05:18 AM
re: Mobile Skype: Quality Issues?
What is stopping some organized hackers from creating a network of 'zombie' computers (via worms, adware, spyware, etc.) to perform DDoS or similar attacks on our phone system?


SIP has been designed as a stateless protocol with this contingency in mind. A SIP message consumes next to no resource on the proxy and so it is next to impossible to send enough messages to hinder its operation.
stephenpcooke 12/5/2012 | 2:05:18 AM
re: Mobile Skype: Quality Issues? optical_man, thanks for the response. I guess the difficulty that I am having is that, as long as the POTS network is linked to any other network whose members can be programmed in any way and are accessible to the general public, the telephone network is vulnerable. I don't have faith in anyone being able to 'fix' this with another box and/or accompanying software.

The point is: no telecom network equipment that is connected to the Internet, in any way, can be classified as meeting the NEBS requirement of having 99.999% uptime in a year.
stephenpcooke 12/5/2012 | 2:05:17 AM
re: Mobile Skype: Quality Issues? 'next to no resource on the proxy' what does this mean exactly and how does it work when applied to thousands of computers all sending these messages?
dljvjbsl 12/5/2012 | 2:05:15 AM
re: Mobile Skype: Quality Issues? 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
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