HFC-Card: Crackle in one way

I´m Dennis and from Germany. I had a big Problem, but no one in the german IP-Phone-Forum can solve that. First, sorry for my bad english :smile:.

A HFC-S-Card(Telekom Teledat 220) is plugged in my *( 1.2.14-BRIstuffed-0.3.0-PRE-1y). No error in Asterisk or Zaptel is shown.
A Crossover-ISDN-cable(about 5 metres long) going to my terminaladapter (Telekom DaTeWe TA 33 Clip). In there I plugged two “analog”(not ISDN) telephones. When I make a dial over Sip I can understand my partner super. But my partner hear many crackle. When i dial intern(zap), the crackler will be more.

hannibal:/etc/asterisk# vi ./zapata.conf

switchtype = euroisdn
signalling = bri_net
overlapdial = yes
immediate = no
group = 1
context = test
 channel => 1-2
hannibal:/etc# vi ./zaptel.conf

Can anyone help me?


It can be many issues.
I had problems with pops/crackles on zap and some automated sip/iax calls.
Turned out to be an IRQ conflict.
I went into the bios and disabled everything I could.
Then logged on as root
cat /proc/interrupts

which listed all my irqs
make sure your phone cards don’t share anything.
your english is a lot better than my german! :laughing:

Thanks for the answer!
The IRQ of my Card is not shared with others.
I don´t now, what I can make now.


I am not familiar with your hardware. Perahps someone else can help.

You may want to try:

  1. iax2 softphone such as Yakaphone
    2.Trace your calls over the internet with Wireshark at