Sorry for the delay in replying. I hadn't fully tested the implementation. I think you have not loaded your derived h224 handler through the H323EndPoint function override I specified in the last email Simon -----Original Message----- From: h323plus-bounces@lists.packetizer.com [mailto:h323plus-bounces@lists.packetizer.com]On Behalf Of mohammad alam Sent: Thursday, January 10, 2008 5:56 PM To: h323plus@lists.packetizer.com Subject: [h323plus] FECC H.224/H.281 Implementation hi Simon As you suggested I have added H323_H224Capability(). The brief code is H323_H224Capability *p = new H323_H224Capability(); capabilities.Add(p); in a class derived from H323EndPoint. The watch window here doesnot show much. But exe crashes in BOOL H323_H224Channel::Start() at h224Handler->StartTransmit(); I think it is not getting pointer right Can you guide me from there. alam.