benny, Is it possible to bind SIP messages belong to a dialog into the same SIP worker thread? Pls consider below SIP msg flow: UAC UAS --> INVITE--> <-- 100 <-- <-- 180 <-- <-- 487 <-- --> ACK --> --> CANCEL -> Yes, it seems UAC is wrong sending CANCEL after ACK. But it is possible UAC send CANCEL before 487 which delayed by network jitter. In theory, there maybe problem when two sip worker thread handling ACK and CANCEL at the same time.For example, ACK thread will try to destroy tsx and its mutex when entering DESTROY state. But before this CANCEL thread got tsx mutex. I know it will be rare and I couldn't use sipp to repeat this at testbed also.But it will be helpful if we can asign messages of one dialog to the same worker thread. regards, Gang -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.pjsip.org/pipermail/pjsip_lists.pjsip.org/attachments/20090522/39ed91b6/attachment.html>