Thanks bo shi for your useful information. Before asking any question I want share the purpose of my project.I want audio conversation between two PCs.To do that which source file I have to include in #include in debug(I am using PJPROJECT1.10).Or I have to develope source code for that???Thanks in advance. Regards Pranab Bangalore -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.pjsip.org/pipermail/pjsip_lists.pjsip.org/attachments/20110607/218f0f59/attachment.html>