asterisk users - May 2010 - asterisk and gnokii on same server: scratchy sound

Hi,

Has anyone tried to use gnokii to send/receive SMS messages via serial or USB
with AT commands while running Asterisk?

Some of my calls have a "scratchy sound" once in a while. It
doesn't seem to be due to packet loss but some kind of interference (CPU is
ok, etc.). I've noticed some coincidence in time between this scratchy sound
and the gnokii process. I have a bash script that calls gnokii periodically to
send/receive messages. The bad audio quality does not *always* appear when the
gnokii process is up but just *sometimes*. If I stop my script, thus gnokii, it
seems that audio quality is fine overall.

What I still don't quite understand is who's responsible for this audio
problem: gnokii itself (I don't think so), the GSM radio signal nearby
(about 2 meters) or the data sent through the serial port/cable.

The third explanation is the most probable but I'd like to know other
people's opinions.

Thanks,

Vieri