[Asterisk-Users] Terrible crackling on analogue line and X100P card

[Rich Adamson]

> I'm experiencing terrible trouble with crackling and noise on an
> analogue line connected to an X100P (compatible) card. I've checked the
> line with a normal analogue phone and it works fine, clear as a bell,
> but any outgoing or incoming calls to Asterisk are almost completely
> drowned out by loud crackling.
> 
> I've attempted to adjust the RX and TX gains, but to no avail. There's
> also an echo, but only one way. I'm assuming this is a separate issue so
> I've not done much to investigate that, but I may be wrong so if it is
> related does anyone have any suggestions?
> 
> I never had this trouble with ISDN, but then I wouldn't would I? :)
> 
> If anyone can wave a magic wand, or at the very least point me to a
> website where I can get my own magic wand, please let me know.

What country are you in, and does the chipset on the compat card
support the telco standards in your country?

If the chipset doesn't match your telco standards, there is a high
probability you won't get rid of the echo. If it does match, then try
 echotraining=800
 echocancel=yes

Regarding the crackling noise, have you checked for shared
interrupts (cat /proc/interrupts)?

If you run "cat /proc/interrupts" every ten seconds, do you see
calculated interrupt values of about 1,000?

Go to /usr/src/zaptel directory and run
 ./zttest
Do you get something close to 100% over some period of time?

What version of asterisk are you running?