asterisk users - Aug 2005 - RE: Noise on ZAP channel

I have a couple SIP phones on a PIII 1Ghz 256MB * server with a TDM01B
connected to the PSTN.  Calls between SIP phones are clear.  Calls to the
PSTN are quite noisy.  The other person does not hear noise but I hear quite
a bit.  It is not an annoying sound but definitely much noisier than typical
PSTN or even cell phone calls.  
 
I believe I have a TDM400P REV H card.  I definitely don't have any IRQ
issues.  Everything not required is disabled in BIOS.  Zaptel drivers have
been compiled with defaults and with MMX and other enhancements.  Have tried
V1.0.9.1 and current 1.2 beta1 software.  Nothing changes.  Tried telco PSTN
connection and VoIP provider connection via ATA which both sound clear when
connected directly to an analog phone. Nothing changes.  Tried adjusting
RX/TX gain and echo cancellation in zaptel.conf.  Nothing changes.
 
 Does any one have any ideas?  Could my FXO module be bad?
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On 8/29/2005, "canuck15" <canuck15@hotmail.com>
wrote:
>
> I have a couple SIP phones on a PIII 1Ghz 256MB * server with a TDM01B
> connected to the PSTN. Calls between SIP phones are clear. Calls to
> the PSTN are quite noisy. The other person does not hear noise but I
> hear quite a bit. It is not an annoying sound but definitely much
> noisier than typical PSTN or even cell phone calls.
>
> I believe I have a TDM400P REV H card. I definitely don't have any IRQ
> issues. Everything not required is disabled in BIOS. Zaptel drivers
> have been compiled with defaults and with MMX and other enhancements.
> Have tried V 1.0.9.1 and current 1.2 beta1 software. Nothing changes.
> Tried telco PSTN connection and VoIP provider connection via ATA which
> both sound clear when connected directly to an analog phone. Nothing
> changes. Tried adjusting RX/TX gain and echo cancellation in
> zaptel.conf. Nothing changes.
>
> Does any one have any ideas? Could my FXO module be bad?
Sure - it could be - I would check it in another TDM400 slot on the
card to make sure. Also - an outside chance - make sure Tip and Ring
are correct. You could be getting ground loops - depends on the noise.

Brett