asterisk users - Mar 2005 - Message waiting/station busy conflict?

Greetings list,

We are having a puzzle with * (asteriskathome 0.5) and SIP phones 
(SPA2000 ATA's). If callwaiting is enabled, everything (including call 
waiting) is normal. If callwaiting is turned off, the phone will not 
accept incoming calls and the call goes straight to whatever is 
programmed for the busy voicemail response. It doesn't matter whether 
reinvite is on or off, or whether the phones are registered or not.  
database show looks like

/CALLTRACE/2369                                   : 2368
/CALLTRACE/2370                                   : 2368
/CW/2368                                          : ENABLED
/CW/2369                                          : ENABLED
/SIP/Registry/2368                                : 
6x.xxx.xx.xx:5060:3600:2368:sip:2368@6x.xxx.xx.xx:5060
/SIP/Registry/2369                                : 
6x.xxx.xx.xx:5061:3600:2369:sip:2369@6x.xxx.xx.xx:5061

Here is the relevant snip from the log. What did I leave out?

Mar 17 12:12:09 VERBOSE[1348]:   == Manager 'admin' logged on from
127.0.0.1
Mar 17 12:12:09 DEBUG[1348]: Manager received command 'command'
Mar 17 12:12:09 DEBUG[1348]: Manager received command ''
Mar 17 12:12:09 DEBUG[1348]: Manager received command 'Logoff'
Mar 17 12:12:09 VERBOSE[1348]:   == Manager 'admin' logged off from 
127.0.0.1
Mar 17 12:12:09 DEBUG[1348]: Unable to find key '2369' in family
'CW'
Mar 17 12:12:09 VERBOSE[1348]:   dialparties.agi: Extension 2369 has 
call waiting disabled
Mar 17 12:12:09 DEBUG[1348]: Unable to find key '2369' in family
'CFB'
Mar 17 12:12:09 VERBOSE[1348]:   dialparties.agi: Max calls of 1 
exceeded - deleting from dial
Mar 17 12:12:09 VERBOSE[1348]:   dialparties.agi: Dial string is empty - 
nothing to do
Mar 17 12:12:09 VERBOSE[1348]:   dialparties.agi: Was direct call, 
jumping to priority 23
Mar 17 12:12:09 VERBOSE[1348]:     -- AGI Script Executing Application: 
(NoOp) Options: ()
Mar 17 12:12:09 VERBOSE[1348]:     -- AGI Script dialparties.agi 
completed, returning 0
Mar 17 12:12:09 VERBOSE[1348]:     -- Executing 
ESC[1;36;40mWaitESC[0;37;40m("ESC[1;35;40mSIP/2368-f359ESC[0;37;40m", 
"ESC[1;3
5;40m2ESC[0;37;40m") in new stack
Mar 17 12:12:11 VERBOSE[1348]:     -- Executing 
ESC[1;36;40mVoiceMailESC[0;37;40m("ESC[1;35;40mSIP/2368-f359ESC[0;37;40m",
"
ESC[1;35;40mb2369ESC[0;37;40m") in new stack
Mar 17 12:12:11 DEBUG[1348]: Difference is 39520, ms is 4960
Mar 17 12:12:11 VERBOSE[1348]:     -- Playing 
'voicemail/default/2369/busy' (language 'en')