[Asterisk-Users] four wildcards in a single pc

[Jim Van Meggelen]

> -----Original Message-----
> From: asterisk-users-bounces at lists.digium.com 
> [mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of 
> Grady Trew, Jr.
> Sent: December 13, 2004 4:15 PM
> To: 'Asterisk Users Mailing List - Non-Commercial Discussion'
> Subject: RE: [Asterisk-Users] four wildcards in a single pc
> 
> 
> > Getting dedicated IRQs for the cards is a minor problem compared to 
> > what happens when you have four cards hammering away mercilessly at 
> > the chipset and CPU of your motherboard; 1000 IRQs per second, per 
> > card. Nobody's really sure what's wrong, but it causes problems for 
> > pretty nearly everyone.
> 
> Would the same issues arise with the use of a single 
> Voicetronix 12 port card?  What about using 2 of them in the 
> same machine?

The problem isn't _exactly_ the volume of interrupts, but rather the
need to have each one serviced immediately, and none get missed. The
Zaptel cards are unique in that they do not have a DSP (Digital Signal
Processor - a chip that handles audio) on board, and thus must get the
CPU to perform this. The job gets done, but the human ear hears about
any samples that get missed. Mostly, this problem seems to show up as
echo.

Any other telephony card will tend to have it's DSPs on board, and thus
will generally be less succeptable to this problem. I couldn't speak
about the Audiotronix cards per se, but I am very interested in them.

Ultimately, any time you run audio through a PC you need to be sure the
system is up to the task. The more calls/connections happening, the more
chances that a delay will occurr. _any_ delay will generally be heard by
the users as _something_ (echo, static, distortion, clicks, pops, etc).