I'm trying to sending instant message working with pjsua2,but I don't know how to define call_id this is my code ,I wish anyone can help me. public void makeInstantMessage() { MyCall call = new MyCall(account, 0);//the second argument is call_id,but I don't know how to define SendInstantMessageParam prm=new SendInstantMessageParam(); prm.setContent("from me:new message?"); prm.setContentType("text/plain"); SipTxOption sipTxOption=new SipTxOption(); sipTxOption.setTargetUri("sip:1002 at 192.168.0.107"); sipTxOption.setMsgBody("zzzzzzz"); prm.setTxOption(sipTxOption); try { call.sendInstantMessage(prm); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.pjsip.org/pipermail/pjsip_lists.pjsip.org/attachments/20140525/031674f0/attachment.html>