[Asterisk-Users] Noise on ZAP channel

[Matt]

I've been strugling with this for two days now and I'm making no progress at
all.  (I've checked been all over the WIKI and google).

The issue is :
I've installed a Digium X100P into my * box, 
configured it to call out over my BT analog line, 
every call I make is horribly noisy, 
there is a background hum on the line which sounds electrical.  

To troubleshoot 
I've plugged an analog line directly into the BT line there is no noise.  
I've * onto a brand spanking new machine incase it was the PSU in the PC
causing the grief in the old machine, but still no luck.

The PC is a P4 with 256MB of RAM and IDE drives. It's doing nothing except
handle one SIP endpoint - which is a cisco 7960G.  Codec is ulaw.

Cat /proc/interpupts gives:
           CPU0
  0:     155092          XT-PIC  timer
  1:          4          XT-PIC  keyboard
  2:          0          XT-PIC  cascade
  3:          0          XT-PIC  ehci_hcd
  5:    1510338          XT-PIC  wcfxo
  7:          0          XT-PIC  usb-uhci
  8:          1          XT-PIC  rtc
  9:      14783          XT-PIC  eth0
 10:          0          XT-PIC  usb-uhci
 11:          0          XT-PIC  usb-uhci
 12:          7          XT-PIC  PS/2 Mouse
 14:       4597          XT-PIC  ide0
 15:          0          XT-PIC  ide1
NMI:          0
ERR:          0

Here is the relevant part of /etc/zapatel.conf

fxsls=1
loadzone=uk
defaultzone=uk

Here is the /etc/asterisk/zapatel.conf

[channels]
language=uk
context=default
signalling=fxs_ls
hidecallerid=no
cancallforward=yes
echocancel=yes
echocancelwhenbridged=yes
echotraining=yes
relaxdtmf=yes
rxgain=0.0
txgain=0.0
group=1
callgroup=1
pickupgroup=1
immediate=no
busydetect=yes
callprogress=yes
musiconhold=default
channel=>1

Any help would really be appriciated.

Regards

Matt