Re: [Asterisk-Users] Call quality problems

2006-02-25 Thread Doug Lytle

Michael Welter wrote:
I'm having difficulty with an Asterisk system.  The external party has 
very good call quality, but the internal party hears clipping and drop 
outs.




RX Gains too high
IRQ sharing of the of the ZAP device
High load of the machine

Are a few that come to mind.

Doug

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deserve neither Liberty nor Safety.


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Re: [Asterisk-Users] Call quality problems

2006-02-25 Thread Michael Welter



Doug Lytle wrote:

Michael Welter wrote:
I'm having difficulty with an Asterisk system.  The external party has 
very good call quality, but the internal party hears clipping and drop 
outs.




RX Gains too high
IRQ sharing of the of the ZAP device


There is no ZAP device (it is a SIP-only implementation) and there are
no interrupts being shared.


High load of the machine


The machine is totally idle.

The T1 vendor noticed 2% packet loss during a ping flood originating
from outside.  We changed the Cisco IAD, and there is no longer packet
loss, but we still have the clipping.

Asterisk 1.2.4.



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Michael Welter
Telecom Matters Corp.
Denver, Colorado US
+1.303.414.4980
[EMAIL PROTECTED]
www.TelecomMatters.net
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Re: [Asterisk-Users] Call quality problems

2006-02-25 Thread Doug Lytle

Michael Welter wrote:

Doug Lytle wrote:

Michael Welter wrote:

The machine is totally idle.

The T1 vendor noticed 2% packet loss during a ping flood originating
from outside.  We changed the Cisco IAD, and there is no longer packet


I've noted from employees that the volumes levels on the phones 
themselves, when set too high will cause crackling.  Does the crackling 
coincide with talking on the local side?


What firmware are you running on the Polycoms?

Doug

--
Ben Franklin quote:

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deserve neither Liberty nor Safety.


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Re: [Asterisk-Users] Call quality problems

2006-02-25 Thread Michael Welter



Doug Lytle wrote:

Michael Welter wrote:

Doug Lytle wrote:

Michael Welter wrote:

The machine is totally idle.

The T1 vendor noticed 2% packet loss during a ping flood originating
from outside.  We changed the Cisco IAD, and there is no longer packet


I've noted from employees that the volumes levels on the phones 
themselves, when set too high will cause crackling.  Does the crackling 
coincide with talking on the local side?


What firmware are you running on the Polycoms?


I'm not on site, but I remember 1.6.4.

It's not really crackling or popping that's the problem.  The problem is
with dropouts.  It also seems that the trailing edge of each word will
sometimes be lost (possibly a dropout).

If you're familiar with the WWV time signal (303-499-7111), for the
first 45 minutes of each hour there is a tone interrupted by a click
every second (during the last 15 minutes it's just the clicks).  When I
listen to this on the Asterisk system, the tone only lasts for a
fraction of a second and then silence until the next click.

Is the phone (or Asterisk) performing echo suppression that drops the
last part of the tone?

Also, there are no ZAP cards in the system.  What timing source does SIP
use to play the incoming media stream?

Thanks for your comments, Doug.

--
Michael Welter
Telecom Matters Corp.
Denver, Colorado US
+1.303.414.4980
[EMAIL PROTECTED]
www.TelecomMatters.net
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Re: [Asterisk-Users] Call quality problems

2006-02-25 Thread Doug Lytle

Michael Welter wrote:



I'm not on site, but I remember 1.6.4.

I had in place 1.6.2, and had way to many problems with it.  I reverted 
back to 1.5.2 and things cleared up.




Is the phone (or Asterisk) performing echo suppression that drops the
last part of the tone?


I believe the phone does some E.C. along with Asterisk.


Also, there are no ZAP cards in the system.  What timing source does SIP
use to play the incoming media stream?


I think the only time you need a timing source is if you are mixing 
audio streams, i.e. meetme, MOH.  In which case you'd probably need to 
run ztdummy.


Doug

--
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deserve neither Liberty nor Safety.


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Re: [Asterisk-Users] Call quality problems

2006-02-25 Thread Michael Welter



Doug Lytle wrote:



I think the only time you need a timing source is if you are mixing 
audio streams, i.e. meetme, MOH.  In which case you'd probably need to 
run ztdummy.


Yes , ztdummy is running.

I'm going to (temporarily) put a TDM card in the system just to 
eliminate that possibility.



--
Michael Welter
Telecom Matters Corp.
Denver, Colorado US
+1.303.414.4980
[EMAIL PROTECTED]
www.TelecomMatters.net
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[Asterisk-Users] Call quality problems

2006-02-24 Thread Michael Welter
I'm having difficulty with an Asterisk system.  The external party has 
very good call quality, but the internal party hears clipping and drop outs.


The WAN comes in from the Cisco IAD and into a LAN switch (DLink 
DGS-1005D w/ 802.1p) where the two public IPs are switched to different 
devices.  One device is a FireBox device controlling a separate LAN with 
VPNs.  The other device is eth0 on the Asterisk system.


On the Asterisk eth1 is a 3Com 2226 LAN switch which connects Polycom 
IP501 phones.  There are no PCs on this voice LAN.  All ports on all LAN 
switches indicate full duplex.  The quality problem doesn't appear to be 
volume related (a single call still has problems).


The Polycom IP501s use SIP to the PBX, and the PBX uses SIP to the provider.

The normal WWV time signal consists of a constant tone that is 
interrupted every second by a click.  On the Polycom, each click can be 
heard, the tone starts, but the tone is clipped and there is silence 
until the next click.


I've verified that QoS is enabled in the IAD.

I would appreciate your thoughts.

Thanks,

--
Michael Welter
Telecom Matters Corp.
Denver, Colorado US
+1.303.414.4980
[EMAIL PROTECTED]
www.TelecomMatters.net
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