We setup a CMECSTAListener to monitor a phone extension events. However, after received the first "ADDRESS_ACTIVATED" event, all other events has been dropped and the listener onNotification method is never invoked. Got error message: "call is null, not able to construct the topo, drop the event".  Anybody knows why?  Thanks in advanced.
 
Below is the log output from my console:
 
[2010-07-13 14:49:47,812] INFO com.cisco.cme.cti.siputil.DsSipInviteDialogNonInviteProcessInterfaceImpl Request received
[2010-07-13 14:49:47,812] INFO com.cisco.cme.cti.siputil.DsSipInviteDialogNonInviteProcessInterfaceImpl ------------------- request ------------------
[2010-07-13 14:49:47,812] INFO com.cisco.cme.cti.siputil.DsSipInviteDialogNonInviteProcessInterfaceImpl INFO sip:101_0013C3D664D7@192.168.30.166:5060;transport=tcp SIP/2.0
Via: SIP/2.0/TCP 192.168.1.88:5060;branch=z9hG4bK3C661
Max-Forwards: 69
To: CME_SDK <sip:101_0013C3D664D7@csta-sdk>;tag=ds2e9594bb
From: <sip:101@192.168.1.88>;tag=446DD8-16BE
Call-ID: 12790469607502@192.168.30.166
CSeq: 101 INFO
Content-Length: 390
Date: Tue, 13 Jul 2010 18:55:31 GMT
User-Agent: Cisco-SIPGateway/IOS-12.x
Timestamp: 1279047357
Contact: <sip:101@192.168.1.88:5060;transport=tcp>
Content-Type: application/csta+xml
Content-Disposition: signal;handling=required

<?xml version="1.0" encoding="UTF-8"?>
<HeldEvent xmlns="http://www.ecma-international.org/standards/ecma-323/csta/ed3">
<monitorCrossRefID>0000000D</monitorCrossRefID>
<heldConnection>
<deviceID>tel:101</deviceID></heldConnection>
<holdingDevice>
<deviceIdentifier>tel:101</deviceIdentifier></holdingDevice>
<localConnectionInfo>hold</localConnectionInfo>
<cause>normal</cause></HeldEvent>
[2010-07-13 14:49:47,812] INFO com.cisco.cme.cti.siputil.DsSipInviteDialogNonInviteProcessInterfaceImpl --------------- end of request ---------------
[2010-07-13 14:49:47,812] INFO com.cisco.cme.cti.CMECSTAAbstractSession Session: dispatch...
[2010-07-13 14:49:47,812] INFO com.cisco.cme.cti.cstaxmlutil.EventFactory com.cisco.cme.cti.jaxbgen.ecma323ed3.LocalDeviceID
[2010-07-13 14:49:47,812] INFO com.cisco.cme.cti.event.CMECallNotification CallNotification: call is null
[2010-07-13 14:49:47,812] INFO com.cisco.cme.cti.CMECSTAAbstractSession Session.dispatch: Receive notification...
[2010-07-13 14:49:47,812] INFO com.cisco.cme.cti.CMECSTAAbstractSession Session.dispatch: group=EVENTGROUP_CSTA_CALL_NOTIFICATION
[2010-07-13 14:49:47,812] INFO com.cisco.cme.cti.CMECSTAAbstractSession Session.dispatch: type=CALL_CONNECTION_HOLD
[2010-07-13 14:49:47,812] INFO com.cisco.cme.cti.CMECSTAAbstractSession Session.dispatch[CALL_CONNECTION_HOLD]: call is null, not able to construct the topo, drop the event

We figured this out. Our incoming calls are from Call Manager, and the CCM talks the CME via H.323 gateway. Once we changed the H.323 gateway to a SIP trunk, it starts working.
 
However, there are still potential issues because we have no control of our customer's CCM settings.