Hi, Please reply as soon as possible ,it is important .I got block from 1 month on this point . I am using the PJSIP version 2.1.0 on the OS X Yoesmite please let me know where i am doing wrong .After sending message app get crash and showing error *Assertion failed: (mutex->owner == pj_thread_this()), function pj_mutex_unlock, file ../src/pj/os_core_unix.c, line 1287.* *I am sending message like this * *eturn input - : hi{* *}* *2016-02-10 10:00:51.263 RNetCall[12571:334714] * *Entered in Function:tableAttributedString * *2016-02-10 10:00:51.263 RNetCall[12571:334714] * *Entered in Function:tableCellAttributedStringWithString * *2016-02-10 10:00:51.263 RNetCall[12571:334714] * *Exited from Function:tableCellAttributedStringWithString * *2016-02-10 10:00:51.264 RNetCall[12571:334714] * *Exited from Function:displayMessage: fromUser: * *10:00:51.264 mydll.c !sendMsgtostack - Msg Type = 67, Message Text = MESSAGE_INIT_MSG* *Buddy list:* * [ 1] <?> sip:449320520681@www.rnetcallclient.com:5060 <http://sip:449320520681@www.rnetcallclient.com:5060>* *Choices:* * 0 For current dialog.* * -1 All 1 buddies in buddy list* * [1 - 1] Select from buddy list* * URL An URL* * <Enter> Empty input (or 'q') to cancel* *Send IM to: 10:00:51.264 pjsua_core.c .TX 608 bytes Request msg MESSAGE/cseq=17235 (tdta0x29f2000) to TCP 115.248.91.197:5060 <http://115.248.91.197:5060>:* *MESSAGE sip:17666053593@www.rnetcallclient.com:5060 <http://sip:17666053593@www.rnetcallclient.com:5060> SIP/2.0* *Via: SIP/2.0/TCP 192.168.2.63:54418;rport;branch=z9hG4bKPj9LFx5UQthoK.juY7XBTCt2hAMMAUne0a* *Max-Forwards: 70* *From: <sip:449320520681@www.rnetcallclient.com <sip%3A449320520681@www.rnetcallclient.com>>;tag=9deVXRYu6Tir9G5jLu90sfMPzqtHmlKX* *To: <sip:17666053593@www.rnetcallclient.com <sip%3A17666053593@www.rnetcallclient.com>>* *Call-ID: CqG-mkJ38K3TtEVOmotaa58jpm0Ghj2U* *CSeq: 17235 MESSAGE* *Accept: text/plain, application/im-iscomposing+xml* *Contact: <sip:449320520681@192.168.2.63:5060;ob>* *User-Agent: RBUZZMac* *Route: <sip:449320520681@115.248.91.197:5060;transport=tcp;lr>* *Content-Type: text/plain* *Content-Length: 2* *hi* *--end msg--* *Assertion failed: (mutex->owner == pj_thread_this()), function pj_mutex_unlock, file ../src/pj/os_core_unix.c, line 1287.* Thanks in advance -- Thanks & Regards, Harish yadav