Hello again everyone!
 
I'm getting a strange result when calling from a Polycom endpoint on FS server "A" to FS server "B":  About one out of ten calls won't complete with the error "SIP/2.0 500 No session set by user".  If I immediately redial the number again it works.
 
Here's my log:  http://pastebin.freeswitch.org/17622
Note the response to the endpoint from server "A" on line 452.
 
Important IP addresses:
Polycom endpoint:  10.15.100.250
Server "A":  10.15.100.20
Server "B":  10.15.100.10
 
I'm on the latest revision (git-2f786a0 2011-10-26 12-57-59 -0500) as well.
 
I appreciate your help.
 
~Brian