This sounds like some sort of host-specific issue. I have run Kamailio across 4 different versions with a whole lot more concurrent registrants than that with no issue. -- Alex Balashov - Principal Evariste Systems LLC 1170 Peachtree Street NE 12th Floor, Suite 1200 Atlanta, GA 30309 Tel: +1-678-954-0670 Fax: +1-404-961-1892 Web: http://www.evaristesys.com/