[Asterisk-Users] Static on inside end of conversation

[Mike McMullen]

----- 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_te405p_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