asterisk users - Apr 2005 - debugging broken/distorted sound with SIP

I've been getting intermittant problems with the sound being
completely broken and distorted on my DID from livevoip.   My * server
is a 3ghz dell poweredge 2650 that is extremely lightly loaded running
CVS HEAD from 3-4 days ago, and it's sitting at my rack at Internap
with plenty of bandwidth.   livevoip is about 10 hops away mostly over
sprint.

Besides some type of network congestion, what other things could be
causing this?

Chris