asterisk users - Mar 2009 - hum noise

HI,
We are experiencing the hum noise when the conversion of 2 parties is
established.  How can we eliminate that noise?   ango

On Sat, 28 Mar 2009, Rilawich Ango wrote:
> We are experiencing the hum noise when the conversion of 2 parties is 
> established.  How can we eliminate that noise?  ango
It depends on the source :)

What computer, what type of connection (Zap (I'm a 1.2 Druid), SIP, IAX), 
what interface hardware (none, t100p, etc.)? Anything else like "the 
channel bank sits atop the isolation transformer for the entire building?"

I built an Asterisk server out of an old Fiire Station. It's Via micro-atx 
in a "shoe-box" and a tdm400. Having everything crammed into such a
small
space put the horizontally mounted tdm card millimeters above the CPU. The 
noise during "dialtone" was so bad I scrapped the project there and
then.

Thanks in advance,
------------------------------------------------------------------------
Steve Edwards      sedwards at sedwards.com      Voice: +1-760-468-3867 PST
Newline                                             Fax: +1-760-731-3000

> I'd suggest calling an echo test or playback(silence) extension on your
> asterisk from the SIP phone.  If there's hum, then it's almost
certainly
> coming from the phone (my bet would be a dodgy power supply).
Probably also worth checking there are no cellphones near either endpoint. They
seem to have a habit of introducing hum into otherwise perfect calls.

As an aside, one does wonder why there's such inadequate shielding against
interference on SIP phones, given that most environments in which they'll be
used will also have a cellphone on the desk.

Regards,

Chris