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Is VOIP Over WLAN DOA?
prostoalex writes "Voice-over-IP in Wireless LAN environment - a futurist's dream of always-on always-connected service. Guy Kewney from eWeek tests the technologies that try to satisfy this market today and finds nothing but disappointment. " The best result we got was that just once, I heard his voice with a delay of about 15 seconds, saying "You just have to speak up!"--which was part of a 20-second burst of speech from him. The rest was lost.""
Well i have used stantaphone over my home wifi worked ok (1-1.5 sec delay) normal for anything of that nature.
I couldn't accept incoming calls, I kept getting a busy signal, but I got my email (the article writer didn't) and even made a few calls. Quality was fairly good, and there was only a delay of a a second or so.
802.11 standard was modeled around having a CSMA/A algorithm that tried to be as much like Ethernet as possible. There is no provision in the BASIC standard to provide for clients to shut up for higher priority voice clients at all! This means that a data client can blow the voice guy to kingdom come.
There are extensions to the 802.11 standard like 802.11e and WME that will allow priority queuing and some minimalistic scheduling to take place. Other companies play tricks with the protocol to allow for voice clients to perform better under the BASIC standard but there are drawbacks.
In the end, it is too early to judge VOIP over WLAN because clients and access points have yet to adopt extensions to the basic standard.
-Ho
A collegue of mine has VPN over DSL to a corporate network. They do all their phones via VOIP. If you send him a ~1MB email while he's on the phone, the call goes down the toilet. Not exactly a "new millenium experience".
Engineering is the art of compromise.
Shoot, we used iChatAV rather successfully from Auckland, New Zealand to Salt Lake City for remote collaboration in a lab environment rather successfully with hardly any delay whatsoever. In fact, I routinely used (and still use) iChatAV with a wireless connection, so I do not understand what this is all about.
Visit Jonesblog and say hello.
My main phone line comes over a 6.1 mile 802.11b link. I use Asterisk PBX with the IAX protocol to bridge the calls.
And my Grandstream SIP phone works great attached to a Linksys WET-11 client bridge.
And my Ipaq runs IAXComm just fine over it's wireless card to use as a netphone.
Does the battery life suck... yes... does it work and show promise... YES!
Just because people have problems with these cheap (as in quality)(usually SIP or H.323 based) piece of crud phones doesn't mean the technology and possibilities are not still there. SIP is VERY prone to problems from NAT (which many wireless networks use of course).
Anyways... for my 2 cents though I say... just give it time.
Telcos have alot of dark fibre in the States. Most people assume that's optical fibre...but it's actually moral fibre.
Of course, the new technology will have glitches. I may just be lucky. However, I think the story submitter pronounces wireless VOIP dead far too early. If, at this early date in the life of the technology, a Mickey Mouse set-up like mine can work, then the future for serious, enterprise level applications seems bright.
You can simulate a VoIP call and get the MOS voice quality score. So if you want to see how your Wireless setup fares, visit testyourvoip.com.
Even if you don't care about VoIP, it is a useful test of the latency and bandwidth of your connection. VoIP is pretty sensitive to late packets so this tool highlights connectivity problems.
-ben
...one of our plants in Ohio. The install was a little rocky, and many of the features you'd find in any circuit-based system were simply non-existant or poorly implemented.
Now, that said, I put the system on its own POE switches and isolated network. Nearly 100 phones and the voice quality is superb. As a matter of fact, I had to introduce some comfort-noise because if nobody was talking, you couldn't tell you were even connected to anyone. It was really that clear. The POTS connection was done with a single PRI span, so calls were digital end-to-end.
I had to place two of the ephones on a remote end of a 10MB fiber link. They worked flawlessly. I then tried a single phone on a WIFI bridge, and it worked flawlessly.
Back to the article... The protocol the phones talk to each other using is g729. It uses roughly 9.6K worth of bandwidth, and sends packets every 20ms or so. A quality secured WiFi connection without any interference can support at least 25 to 30 phones before you start having channel speed or bandwidth problems.
In summary, a properly architected system has NO problems, whereas a system implemented over old, crappy hardware will have problem after problem.
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> shoot, we used iChatAV rather successfully from Auckland,
> New Zealand to Salt Lake City for remote collaboration in a lab
> environment rather successfully with hardly any delay
> whatsoever
Yeah. I do this all the time.
Ingredients:
1. PowerBook G4
2. Mac OS X 10.3
3. iChat AV
4. AirPort (802.11b version)
5. Comfy bed, little computer lap tray, Collie sitting on your feet (all optional)
Results: no problem at all. No delay noticeable. Voice quality was fine. Voice quality was so good, the whole thing was kind of anti-climatic.
Insert simplistic political, ideological, or personal proselytization here.
Essentially, what we need for VoIP over "any network" is bandwidth allocation based on QoS.
This QoS capability must happens at various OSI layer, like physical layer 802.11, and/or network layer IP. (Transport and application layer QoS are not as effective.)
From IP to IP perspective, IP QoS will be the key for good VoIP.
From WLAN only to WLAN only perspective, WLAN QoS will be beneficial.
In a hybrid physical layer network, with backbone+broadband+ethernet+WLan, IP QoS is the way to go for good VoIP.
However, current IPv4 does not support the needed QoS effectively, and IPv6 is suppose to hold the promise. Ironically, we also see that IPv6 deployment is very slow.
In short, my take is - existing 802.11 is good enough for VoIP, and the problem is actually on the current IPv4, which is not capable to handle QoS.
Hey, that's my password you are typing
VoIP over WLAN has just started. If you work for an intrenched Wireless Phone provider or a Baby Bell you wish that VoIP over WLAN was dead and this is probably just the beginning of the FUD from these guys and their pawns in an effort to hold on to their customers. So my answer is no.. its not dead.