[Asterisk-Users] Static on inside end of conversation

Wed Dec 7 12:34:23 MST 2005

The device that interfaces to the PSTN is the interface that must cancel 
echo.  If I read your post correctly, that is the SAP-3000 and the 
Audiocodes boxes in your case.

Jeff Busch wrote:
> Update on this... And it is still not solved.
> 
> This is actually fairly interesting.  I have two installations at a
> construction company.  They are both running similar class machines (I
> was wrong in my initial post) they are:
> 
> System "A"
> 2.4 ghz Celeron
> 1 gb RAM
> IDE Drives
> Asterisk at Home 1.13 (Asterisk 1.0.9)
> An Audiocodes MP-108 to interface with PSTN
> 9 Polycom IP-500
> Phone system is on 16 port linksys switch.  All PC's are on separate 16
> port switch.  Both switches are plugged into our VPN firewall (Netscreen
> 5xp)
> 
> 
> System "B"
> 2.4 ghz Celeron
> 1 gb RAM
> IDE Drives
> Asterisk at Home 2.1 (asterisk 1.2)
> 5 Sipura SPA-3000  to interface with PSTN
> 12 Polycom IP-500
> Phone and data on NEW Netgear 48 port Smart Switch.  Voice is on Vlan 02
> with QoS set to HIGH.  Data is on Vlan 01 with QoS set to LOW.  Switch
> is connected to Netscreen 5xp VPN firewall
> 
> 
> Polycoms are running the newest possible firmware for this phone:
> Bootrom 2.6.1 and SIP 1.5.2
> 
> 
> Everything is working fine on both systems, but BOTH systems are
> experiencing echo on the IP side of the conversation.  Some phones are
> worse than others.  
> 
> System A is experiencing echo both on internal Station to station calls,
> and on outbound calls.
> System B is experiencing echo on internal station to station calls, and
> no one has complained about echo on outbound calls yet.
> 
> The Polycoms are running G.711u as their 1st configured codec (G711a as
> #2 and G.729AB as #3) and Asterisk is configured to disallow=all &
> allow=ulaw.
> 
> I have searched and searched concerning echo and Polycom phones and
> haven't found anything that seems to be relevant.  Any help would be
> appreciated.
> 
> One more note, I am NOT running TDM4xxp cards on either of these
> machines, so Zaptel information concerning echo wouldn't be relevant,
> correct?
> 
> Thanks!
> 
> 
> Jeff Busch 
> 
> 
> -----Original Message-----
> From: asterisk-users-bounces at lists.digium.com
> [mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Mike
> McMullen
> Sent: Tuesday, November 29, 2005 6:26 PM
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: Re: [Asterisk-Users] Static on inside end of conversation
> 
> 
> ----- Original Message -----
> From: "Jeff Busch" <Jeff.Busch at lewisbuilds.com>
> 
>> Hello,
>>
>> I am running the following configuration:
>>
>> 2.8ghz P4 with 1GB of RAM
>> Audiocodes MP-108 connected to 5 POTS lines Polycom IP-500 phones 
>> Asterisk at Home 1.3 (this is Asterisk 1.0.9)
>>
>> End users are complaining of an echo and static on the inside end (the
> 
>> internal side), but the outside end of the conversation doeesn't 
>> notice anything.
>>
>> Does anyone have any suggestions on troubleshooting / fixing this 
>> problem?
>>
> 
> Hi Jeff,
> 
> I recommend upgrading to Asterisk at home 2.0 which was just released. 
> It uses Asterisk 1.2 and a 2.6.9 based kernel which handles i/o and
> interrupts much better.
> 
> While the link below discusses issues with digium cards, in general the
> interrupts and IDE vs SATA drive discussions are of use no matter what.
> 
> http://www.asteriskguru.com/tutorials/pci_irq_apic_tdm_ticks_te410p_te40
> 5p_noise.html
> 
> I have 2 Digium T400P cards connected to 8 POTS lines and 10 sipura
> spa-841 phones.
> 
> I went through two PCs we had (2.9 GHZ celeron, 2.1HGZ Athlon
> XP) both with IDE drives. I finally declared war on echo and the Rice
> Krispies syndrome (Snap, Crackle, Pop) on the internal end of the
> conversations. 
> 
> I went and bought an ASUS P5LD2 motherboard with 1GB memory, 3.2GHz  P4
> with hyperthreading and a 2MB cache, and a SATA drive. I installed
> Asterisk at Home 2.0. After some minor magic to get the correct merlin
> gigabit ethernet driver for CentOS 4.2, everything came up perfect.
> 
> This was my thanksgiving project and so far sound quality has been
> perfect. No echo and no rice krispies.
> 
> I simulated network load on the system by copying multi-GBs of files
> through the net from another server with scp while I called out and back
> into the system on multiple lines. Even with the scp reporting
> 9.5MB/sec, the phone sound quality was fantastic.
> 
> I then upped the ante by copying multi-gb files on the hard drive which
> when viewing stats with top (hyperthreading shows as 2 CPUs and you run
> the SMP kernel) both CPUs showed no idle time. IO- Wait state never
> greater than 10%. Phone calls were still perfect with no echo or noise.
> Out of the 10 vmails I left as part of the test, only one had
> 3 very faint pops in a 30 second message. They could have come from the
> POTS line for all I know.
> 
> I ran extended phone conversations by calling the Asterisk system from
> our old phone system, picking up the extension on the called SIP phone
> and then playing Law & Order dvd episodes (lots of talking) and placing
> the handset near to the speaker and taking the old phone system handset
> and listening and talking back into it for 30 minutes at a time.
> Necessity is indeed a mother.... ;-) 
> 
> The calls were perfect. I'm amazed at how clear the dvd audio came
> through. 
> 
> I then reversed the process and played the dvd audio through the
> Asterisk system handsets while listening and talking back through the
> old phone handsets.
> 
> After 30 minutes the quality was still excellent.
> 
> 
> Hope you find some of this ramble useful.
> 
> Mike
>  
> 
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