Hi Benny, It's me again. Provide some more detail flow that I encountered. I believe that REFER and KPML are register as Evtsub module to PJSIP core. Please let me know in case of my miss tracing. c. User transfer the call evsub0x1003ae8 UAC subscription created, using dialog dlg0x10039eb4 When the REFER UAC created, we'll get the following log. dlg0x10039eb4 Module mod-evsub already registered as dialog usage, updating the data 0x100xxx And the dlgsub_head will be overwrited later by dlg->mod_data[mod->id] = mod_data; Please have a look for the flow and let me know anything I lost. Thanks! Best Regards! Champion Wang 01/15/2010 _________________________________________________________________ ?????????????????????????????? ? Windows Live Spaces http://home.spaces.live.com/?showUnauth=1&lc=1028 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.pjsip.org/pipermail/pjsip_lists.pjsip.org/attachments/20100115/c0829079/attachment.html>