Hi Samuel, For Implement MWI I use the files which you posted. I have done the following steps in symbian_ua.cpp: After pjsua_init() call : pjsip_mwi_init_module(pjsua_get_pjsip_endpt(), pjsip_evsub_instance()); pjsua_mwi_init(); After pjsua_start() call : pjsua_mwi_start(); Before pjsua_destroy() call : pjsua_mwi_shutdown(); Now there is no error. But how can I find that the module are working properly or not? Waiting for your valuable comments. Nasir -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.pjsip.org/pipermail/pjsip_lists.pjsip.org/attachments/20091018/4debb18b/attachment.html>