[ATLSIP] OSSPhone won't accept incoming calls - responds with 404

[OSS F. A. <ope...@op...>]

Can anyone tell me why various versions of OSSPhone and a separate test program I wrote using ATLSIP respond to incoming calls with
{quote}>>> SIP/2.0 404 Not Found DST: 198.65.166.131:5060:UDP  SRC: 192.168.0.5:5060 enc=0 bytes=567{quote}?

Outgoing calls work.

I'm using a release ATLSIP.DLL built with current sources from CVS as of the morning of 2008-07-23.

Here is the log:
{quote}----------------424:48:10.259----------------
Querying STUN server at stun01.sipphone.com.
This may take a while ... 


----------------424:48:10.732----------------
*** LISTENER STARTED *** [OPAL] 127.0.0.1:5060

----------------424:48:10.733----------------
*** LISTENER STARTED *** [OPAL] 192.168.0.5:5060 [*** DEFAULT LISTENER ***]

SIP event:: SIPInitialized
----------------424:48:10.749----------------
>>> REGISTER sip:proxy01.sipphone.com SIP/2.0 DST: 198.65.166.131:5060:UDP  SRC: 192.168.0.5:5060 enc=0 bytes=620

----------------424:48:10.841----------------
<<< SIP/2.0 401 Unauthorized  SRC: 198.65.166.131:5060:UDP enc=0 bytes=587

----------------424:48:10.846----------------
>>> REGISTER sip:proxy01.sipphone.com SIP/2.0 DST: 198.65.166.131:5060:UDP  SRC: 192.168.0.5:5060 enc=0 bytes=849

----------------424:48:10.944----------------
<<< SIP/2.0 200 OK  SRC: 198.65.166.131:5060:UDP enc=0 bytes=548

SIP event:: LoginSuccessful
----------------424:48:32.422----------------
<<< INVITE sip:17476331234@72.240.235.122:21013;transport=udp SIP/2.0  SRC: 198.65.166.131:5060:UDP enc=0 bytes=1200

----------------424:48:32.424----------------
>>> SIP/2.0 100 Trying DST: 198.65.166.131:5060:UDP  SRC: 192.168.0.5:5060 enc=0 bytes=452

SIP event:: IncomingCall: callerInfo="sip:174...@pr..."
----------------424:48:33.148----------------
>>> SIP/2.0 404 Not Found DST: 198.65.166.131:5060:UDP  SRC: 192.168.0.5:5060 enc=0 bytes=567

----------------424:48:33.240----------------
<<< ACK sip:17476331234@72.240.235.122:21013;transport=udp SIP/2.0  SRC: 198.65.166.131:5060:UDP enc=0 bytes=353{quote}

Finest regards,
Bill Root