asterisk users - Apr 2004 - SIP dropouts

Howdy all...

When making SIP calls through my X100P from X-Lite to the PSTN I'm 
getting 3-5 second dropouts in both directions.  I've tried ulaw and 
GSM, but that doesn't seem to make a difference, and the * box is on my 
local net.

Here's my hardware: Celeron 2.4GHz, 512MB, Slackware 9.1, 2 X100P, 1 T100P.

Any ideas what could be happening, or pointers as to how to shoot this 
trouble?

Thanks,

Brad Waite

Sorry, forgot to mention that I set up an extension to play back a long 
MP3.  Other than the occasional 20ms packet being dropped on the floor, 
no other detectable dropouts.

Again, thanks for any pointers.

Brad Waite