That is my first post here so please tell me if I don’t provide you with enough information on my asterisk setup.
I installed an Asterisk 1.4.24 with a DMlink DM1600a card for a call center in China.
Here is a link on the Chinese Ebay-like website to buy the card : http://item.taobao.com/auction/item_detail-0db1-8e39a21a9c1a8fb6af6b4201a4278b0a.htm
My card has 8FXS and 8FXO. It is connected to 8 service lines and 8 analog phones.
The system is working well, the dialplan works, queues work …
I had echo on the 8 analog phones, the agents heard their own voice very loud, but without delay, so I turned on echo canceling in zapata.conf.
The call center has been answering calls for 2 days now with this new pbx, and every agent reported noise on the beginning of many calls.
I turned on monitoring to get this noise recorded. It is very short, less than 1 second, and like 20 very quick taps. It happens twice very often in the beginning of some calls, and sometimes in the middle of calls.
You can download the sound here :
I first thought it was because of echo canceling. I turned it of and it didn’t get rid of the noise.
I checked the IRQ. My card was sharing one with an other piece of hardware. I changed in the bios.
lspci outputs this :
00:0b.0 Communication controller: Tiger Jet Network Inc. Tiger3XX Modem/ISDN interface
Subsystem: Unknown device 8151:0002
Flags: bus master, medium devsel, latency 32, IRQ 18
I/O ports at e400 [size=256]
Memory at ed104000 (32-bit, non-prefetchable) [size=4K]
Capabilities:  Power Management version 2
So my card is using IRQ 18, and it is alone on this IRQ :
cat /proc/interrupts | grep 18
18: 57871772 IO-APIC-fasteoi dmtdm
I am out of ideas, I will also contact the card vendor, and try with an other card.
Do you have any idea ?