Hi, I found a bug in pjsua : When you configure an account with a sip id like that : <sip:user%40test.com at titi.fr> Which is the valid escaped version of an account with an username user at test.com. (I know that's a little bit strange and weird but some users has this configuration ;) ). In this case, when the account is configured to rewrite contact field, it try to rewrite with the *unescaped* username. There is fortunately another check later that raise an error cause of course user at test.com@somewhere is an invalid SIP uri, but the bug is that it should never rewrite to user at test.com@xxxxxxx but to user%40test.com at somewhere instead. I've added a quick fix to my trunk (on CSipSimple project) see : http://code.google.com/p/csipsimple/source/detail?r=572 (there is the diff available). I don't know if it's the right place to put the modification, but it works and fix the bug for me. Regards, R?gis