VOIP Degradation on Wireless Network

Hi all,

I am using a VOIP softphone. When at my office this works fine, but
when I am working from home I get massive jitter and delay in response.

I am wondering if my home wireless network 802.11G could be the cause.
When I connect to my router directly with an ethernet cable, the IP
Softphone seems to work much better with less jitter.

I don't really understand that as my laptop is only a couple of metres
from the router in clear line of site and I have a solid 54MBPS
connection on wireless.

I am not sure if I could also have a latency issue - I seem to have
ping times of 120ms to the my companies' servers in the US which is
where the IP phone exchange is located.

Is it normal to expect much worse performance on an IP softphone when
going over a local wireless network?

cheers for any comments on this.

I would say that it's normal to expect worse performance on wireless
altogether. You have to remember, radio waves are susceptible to many
things that wires arent. Honestly, 120ms on VoIP is a lot, and I'm
surprised you're making calls that are decent at all.

Chris
http://www.netsteady.cc

On 7 Nov 2006 01:50:29 -0800, (E-Mail Removed) wrote in
<(E-Mail Removed) .com>:

>I am using a VOIP softphone. When at my office this works fine, but
>when I am working from home I get massive jitter and delay in response.

That's probably a result of enough wireless interference to cause lots
of transmission errors.

>I am wondering if my home wireless network 802.11G could be the cause.
>When I connect to my router directly with an ethernet cable, the IP
>Softphone seems to work much better with less jitter.
>
>I don't really understand that as my laptop is only a couple of metres
>from the router in clear line of site and I have a solid 54MBPS
>connection on wireless.

Interference can still be a problem. See types and remedies in the
wikis below.

>I am not sure if I could also have a latency issue - I seem to have
>ping times of 120ms to the my companies' servers in the US which is
>where the IP phone exchange is located.
>
>Is it normal to expect much worse performance on an IP softphone when
>going over a local wireless network?

No. Absent interference, latency of Wi-Fi is quite low.

Try different Wi-Fi channels with minimal overlap: 1, 6, and 11.

--
Best regards, FAQ for Wireless Internet: <http://Wireless.wikia.com>
John Navas FAQ for Wi-Fi: <http://wireless.wikia.com/wiki/Wi-Fi>
Wi-Fi How To: <http://wireless.wikia.com/wiki/Wi-Fi_HowTo>
Fixes to Wi-Fi Problems: <http://wireless.wikia.com/wiki/Wi-Fi_Fixes>

(E-Mail Removed) hath wroth:

>I am using a VOIP softphone.

Maker and model number of softphone?
Maker and model number of the wireless router you're using?

>When at my office this works fine, but
>when I am working from home I get massive jitter and delay in response.
>
>I am wondering if my home wireless network 802.11G could be the cause.
>When I connect to my router directly with an ethernet cable, the IP
>Softphone seems to work much better with less jitter.
>
>I don't really understand that as my laptop is only a couple of metres
>from the router in clear line of site and I have a solid 54MBPS
>connection on wireless.
>
>I am not sure if I could also have a latency issue - I seem to have
>ping times of 120ms to the my companies' servers in the US which is
>where the IP phone exchange is located.
>
>Is it normal to expect much worse performance on an IP softphone when
>going over a local wireless network?

Assuming nothing is defective, your home system probably has either a
weak signal, reflection problems, or interference. All of these
result in packet loss (at the MAC layer) which shows up as latency
variations. The few softphones I've tinkered with all have a built in
ping utility. Fire up the utility, and ping your unspecified model
wireless router utility. If your unspecified model (are you getting
the hint?) softphone does not have a ping utility, ping the phones IP
address from another PC on your network that is plugged directly into
your unspecified model wireless router.

You should see *CONSISTENT* ping times with 1 or perhaps 2 msec
latency. However, if you see something like this:

Reply from 192.168.1.50: bytes=32 time=6ms TTL=127
Reply from 192.168.1.50: bytes=32 time=12ms TTL=127
Request timed out.
Reply from 192.168.1.50: bytes=32 time=66ms TTL=127
Reply from 192.168.1.50: bytes=32 time=1ms TTL=127
Reply from 192.168.1.50: bytes=32 time=1ms TTL=127
Reply from 192.168.1.50: bytes=32 time=5ms TTL=127

you have a problem. The normal latency on this wireless link is 1
msec. The other values are packet loss and retransmissions cause in
this case by interference from another nearby network. I can usually
guess the cause by watching the numbers. Do whatever is necessary to
get it to always be 1msec (or less).

If you get fairly consistent ping times, then something else is the
problem. Usually its someone else using your broadband network and
hogging all the outgoing bandwidth. This is why most current routers
have a QoS feature, that will allow prioritization of packets. VoIP
packets come first. File sharing and Peer to Peer networking comes
last. You may also have a worm or trojan horse running on a local PC
that's hogging all the outgoing bandwidth. Try the softphone with all
the other computers in the house turned off and see if that helps.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

"NetSteady" <(E-Mail Removed)> hath wroth:

>I would say that it's normal to expect worse performance on wireless
>altogether. You have to remember, radio waves are susceptible to many
>things that wires arent. Honestly, 120ms on VoIP is a lot, and I'm
>surprised you're making calls that are decent at all.
>
>Chris
>http://www.netsteady.cc

Sorta kinda maybe. 120msec latency is no problem as long as it's a
consistent 120msec latency. For example, I have a customer that uses
Skype and other VoIP phone systems over a DirecWay satellite link.
Latency is typically 800msec. When traffic is minimal and the latency
is consistently 800msec, there's no problem using the satellite link
(except for having to say "over" at the end of each phrase).
Admittedly, that's not very often, but it does work. Similarly, Skype
VoIP works just fine over a dialup connection, which usually has 120
to 200msec latency. The point is that if the latency does not vary,
VoIP will work fine.

In the case of wireless, the minimal latency is basically the
processing time of the devices at each end. Flight time is at the
speed-o-light which is negligible unless you try for long distance
(over 5 mile) links. The effect is the same. Consistent latency will
cause a delay or echo, but not garble the voice. Varying latency will
sound like gargling ball bearing.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Hi,

802.11 uses a CSMA/CA MAC protocol with a exponential backoff contention
window. So, in case of your wireless channel is shared with other
devices (802.11, bluetooth, home devices like microwave ovens, TV
transmiters, etc.) at the same band, then you are making use of the
backoff contention window and then you are using a random time to access
channel. So your jitter can be cancelled by means of buffers. The
greater the buffer the greater delay. But if the buffer is too short you
con run out of it.

Also if you generate packets at a high rate, you can force yourself to
make use of contention window although your wireless networks is made of
one wireless station.

Maybe a first simple solution be a change in transmission channel.

Best regards.

(E-Mail Removed) escribió:
> Hi all,
>
> I am using a VOIP softphone. When at my office this works fine, but
> when I am working from home I get massive jitter and delay in response.
>
> I am wondering if my home wireless network 802.11G could be the cause.
> When I connect to my router directly with an ethernet cable, the IP
> Softphone seems to work much better with less jitter.
>
> I don't really understand that as my laptop is only a couple of metres
> from the router in clear line of site and I have a solid 54MBPS
> connection on wireless.
>
> I am not sure if I could also have a latency issue - I seem to have
> ping times of 120ms to the my companies' servers in the US which is
> where the IP phone exchange is located.
>
> Is it normal to expect much worse performance on an IP softphone when
> going over a local wireless network?
>
> cheers for any comments on this.
>

On Tue, 07 Nov 2006 09:52:55 -0800, Jeff Liebermann
<(E-Mail Removed)> wrote in
<(E-Mail Removed)>:

>"NetSteady" <(E-Mail Removed)> hath wroth:
>
>>I would say that it's normal to expect worse performance on wireless
>>altogether. You have to remember, radio waves are susceptible to many
>>things that wires arent. Honestly, 120ms on VoIP is a lot, and I'm
>>surprised you're making calls that are decent at all.
>>
>>Chris
>>http://www.netsteady.cc
>
>Sorta kinda maybe. 120msec latency is no problem as long as it's a
>consistent 120msec latency. For example, I have a customer that uses
>Skype and other VoIP phone systems over a DirecWay satellite link.
>Latency is typically 800msec. When traffic is minimal and the latency
>is consistently 800msec, there's no problem using the satellite link
>(except for having to say "over" at the end of each phrase).
>Admittedly, that's not very often, but it does work. Similarly, Skype
>VoIP works just fine over a dialup connection, which usually has 120
>to 200msec latency. The point is that if the latency does not vary,
>VoIP will work fine.

Dialup with a good modem should add less than 120 ms latency. If it
adds more than that, either the modem is crappy, or something else is
wrong (e.g., crappy ISP).

--
Best regards, FAQ for Wireless Internet: <http://Wireless.wikia.com>
John Navas FAQ for Wi-Fi: <http://wireless.wikia.com/wiki/Wi-Fi>
Wi-Fi How To: <http://wireless.wikia.com/wiki/Wi-Fi_HowTo>
Fixes to Wi-Fi Problems: <http://wireless.wikia.com/wiki/Wi-Fi_Fixes>

On Tue, 07 Nov 2006 09:39:52 -0800, Jeff Liebermann
<(E-Mail Removed)> wrote in
<(E-Mail Removed)>:

>If you get fairly consistent ping times, then something else is the
>problem. Usually its someone else using your broadband network and
>hogging all the outgoing bandwidth. This is why most current routers
>have a QoS feature, that will allow prioritization of packets. VoIP
>packets come first. File sharing and Peer to Peer networking comes
>last. You may also have a worm or trojan horse running on a local PC
>that's hogging all the outgoing bandwidth. Try the softphone with all
>the other computers in the house turned off and see if that helps.

Another likely cause of high/inconsistent latency is saturation of
broadband uplink, which isn't addressed by the QoS in most low-end
routers. No matter what the packet priority, saturation of the uplink
on typical consumer (asymmetric) broadband results in severe downlink
speed degradation and big latency spikes. The only way to resolve that
is with uplink throttling, either in the client computer or in the
router.

--
Best regards, FAQ for Wireless Internet: <http://Wireless.wikia.com>
John Navas FAQ for Wi-Fi: <http://wireless.wikia.com/wiki/Wi-Fi>
Wi-Fi How To: <http://wireless.wikia.com/wiki/Wi-Fi_HowTo>
Fixes to Wi-Fi Problems: <http://wireless.wikia.com/wiki/Wi-Fi_Fixes>

> Maker and model number of softphone?

Cisco IP communicator 2.0.2.0

> Maker and model number of the wireless router you're using?

BT Homehub (I am in the UK and this is the router supplied by BT who
are my ISP).

> Assuming nothing is defective, your home system probably has either a
> weak signal, reflection problems, or interference. All of these
> result in packet loss (at the MAC layer) which shows up as latency
> variations. The few softphones I've tinkered with all have a built in
> ping utility. Fire up the utility, and ping your unspecified model
> wireless router utility. If your unspecified model (are you getting
> the hint?) softphone does not have a ping utility, ping the phones IP
> address from another PC on your network that is plugged directly into
> your unspecified model wireless router.

When you say ping the phone's IP address, you mean ping the computer
that the phone is running on?


>
> You should see *CONSISTENT* ping times with 1 or perhaps 2 msec
> latency. However, if you see something like this:
>
> Reply from 192.168.1.50: bytes=32 time=6ms TTL=127
> Reply from 192.168.1.50: bytes=32 time=12ms TTL=127
> Request timed out.
> Reply from 192.168.1.50: bytes=32 time=66ms TTL=127
> Reply from 192.168.1.50: bytes=32 time=1ms TTL=127
> Reply from 192.168.1.50: bytes=32 time=1ms TTL=127
> Reply from 192.168.1.50: bytes=32 time=5ms TTL=127
>
> you have a problem. The normal latency on this wireless link is 1
> msec. The other values are packet loss and retransmissions cause in
> this case by interference from another nearby network. I can usually
> guess the cause by watching the numbers. Do whatever is necessary to
> get it to always be 1msec (or less).

First, I pinged my router from the computer where the softphone is
running 72 times and got 2 long response times out of 72 - the rest
were 1ms.

However a few minutes later I tried again and got the following:


Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=150ms TTL=64
Reply from 192.168.1.254: bytes=32 time=38ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=2ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=150ms TTL=64
Reply from 192.168.1.254: bytes=32 time=140ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=150ms TTL=64
Reply from 192.168.1.254: bytes=32 time=140ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=150ms TTL=64
Reply from 192.168.1.254: bytes=32 time=33ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64
Reply from 192.168.1.254: bytes=32 time=1ms TTL=64

So it looks like I have an issue but it's intermittent?

When you say you can guess the cause by watching the numbers, do you
mean that there is some pattern in the dropouts that is consistent with
some other device in the area or what?

>
> If you get fairly consistent ping times, then something else is the
> problem. Usually its someone else using your broadband network and
> hogging all the outgoing bandwidth. This is why most current routers
> have a QoS feature, that will allow prioritization of packets. VoIP
> packets come first. File sharing and Peer to Peer networking comes
> last. You may also have a worm or trojan horse running on a local PC
> that's hogging all the outgoing bandwidth. Try the softphone with all
> the other computers in the house turned off and see if that helps.
>
> --
> Jeff Liebermann (E-Mail Removed)
> 150 Felker St #D http://www.LearnByDestroying.com
> Santa Cruz CA 95060 http://802.11junk.com
> Skype: JeffLiebermann AE6KS 831-336-2558


Thanks for you input on that. This QoS feature - if I have it will it
work automatically or do I need to configure it?

On Tue, 07 Nov 2006 18:50:23 GMT, John Navas
<(E-Mail Removed)> wrote:

>On Tue, 07 Nov 2006 09:52:55 -0800, Jeff Liebermann
><(E-Mail Removed)> wrote in
><(E-Mail Removed)>:
>
>>"NetSteady" <(E-Mail Removed)> hath wroth:
>>
>>>I would say that it's normal to expect worse performance on wireless
>>>altogether. You have to remember, radio waves are susceptible to many
>>>things that wires arent. Honestly, 120ms on VoIP is a lot, and I'm
>>>surprised you're making calls that are decent at all.
>>>
>>>Chris
>>>http://www.netsteady.cc
>>
>>Sorta kinda maybe. 120msec latency is no problem as long as it's a
>>consistent 120msec latency. For example, I have a customer that uses
>>Skype and other VoIP phone systems over a DirecWay satellite link.
>>Latency is typically 800msec. When traffic is minimal and the latency
>>is consistently 800msec, there's no problem using the satellite link
>>(except for having to say "over" at the end of each phrase).
>>Admittedly, that's not very often, but it does work. Similarly, Skype
>>VoIP works just fine over a dialup connection, which usually has 120
>>to 200msec latency. The point is that if the latency does not vary,
>>VoIP will work fine.

>Dialup with a good modem should add less than 120 ms latency. If it
>adds more than that, either the modem is crappy, or something else is
>wrong (e.g., crappy ISP).

I stand corrected. I couldn't remember the latency I was getting for
a dialup modem. Worse, I couldn't find a dilaup modem to even try it.
None of my desktops or laptops have an internal modem. So, I did the
Google thing, found someone expounding on dialup latency, and used
their numbers. Try a Google search for "dialup latency msec" and
notice the rather large numbers it returns.

Looking on the shelf, I see several large boxes full of assorted ISA
and PCI modems. Maybe this is a clue about dialup.

Wow. I also just found a box of Microchannel boards. I wonder what
else is buried behind all the modem boards.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 (E-Mail Removed)
# http://802.11junk.com (E-Mail Removed)
# http://www.LearnByDestroying.com AE6KS