asterisk users - Nov 2005 - IAX softphone's sporadic performance - Keep Alive Issue?

The problem is that my IAX softphone only receives calls sporatically.
  
  I am using both Firefly and Diax (not at the same time!) to connect  from
inside my office network (behind NAT) to my Asterisk (1.0.9) box  in my home
(behind NAT.)  The softphone registers as an extension  no problem and
originates calls perfectly.  The problem is that  incoming calls to Asterisk
frequently do not ring my softphone although  instructed to by the dial command.
My gut tells me that this is a  timing issue and that the office firewall is
closing the connection  just before the call comes in.
  
  Can the frequency of the keep-alive packets be increased?
  
  Below is the output of the CLI.  gcleaves is the name of the IAX2  softphone
extension.  The output says "Called" but the phone does  not ring. 
The other two extensions are on the same network as  Asterisk and ring just
fine.
  
  Any ideas?
  
      -- Accepting AUTHENTICATED call from 192.xxx.xx.xx, requested format = 4,
actual format = 4
      -- Executing  Dial("IAX2/iaxfwd@192.xxx.xxx.xxx:4569/2", 
"SIP/cordless&SIP/telefonica1&IAX2/gcleaves|20|tThH") in new 
stack
      -- Called cordless
      -- Called telefonica1
      -- Called gcleaves
      -- SIP/telefonica1-52dd is ringing
      -- SIP/cordless-d992 is ringing
      -- Registered 'gcleaves' (AUTHENTICATED) at 6x.xxx.xxx.xx:37642
      -- Nobody picked up in 20000 ms
  
  


Geoffrey Cleaves
Skype: gtcleaves
Yahoo! Messenger: gcleaves
IAX: iax:guest@voip.gcleaves.com/gcleaves
FWD: 697925
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