[Users] too many branches for latest X-lite 3

Hello, I have problems with too many branches for latest X-Lite release 1011s stamp 41150. Other phones are working properly. X-Lites are trying to subscribe each 40 seconds with different rinstance strings. Example: mysql> select contact,last_modified from location where username='1538' order by last_modified; +-----------------------------------------------------------+---------------------+ | contact | last_modified | +-----------------------------------------------------------+---------------------+ | sip:1538@158.197.240.237:51092;rinstance=897b6ff9462755eb | 2007-06-13 14:17:41 | | sip:1538@158.197.240.237:51092;rinstance=059223be49bdc5a4 | 2007-06-13 14:18:21 | | sip:1538@158.197.240.237:51092;rinstance=e3b22d920bdd9b61 | 2007-06-13 14:19:00 | | sip:1538@158.197.240.237:51092;rinstance=163058af66fd3b21 | 2007-06-13 14:19:39 | | sip:1538@158.197.10.104:5060 | 2007-06-13 15:10:01 | +-----------------------------------------------------------+------------------- After some time there is 30-90 subscriptions for some users (not for all users of X-lite, but only for lastest Xlite). After some time openser is sending many SUBSCRIBE requests to these users and eats all of CPU, my calls are very slow. I am now trying to play with "max_contacts" registrar parameter set to 5. Is it a problem of X-lite and how to prevent these DOS attacks from wrong softphones? Thank you. SAL