[Freeswitch-users] FS for SIP registrar server

Dear All, I use FS for my wholesale solution. it's work fine over 2000 concurrent in peak hr. so in experience when i use FS for SIP registrar server with out ODBC (but use tmp for db path) i can handle 12,000 active in 1 server (25% CPU). All user send register packet every 3 minutes. Now i need system for handle 500,000 subscriber I have 2 choice 1. use Kamailio for SIP regitrar and use FS for routing and billing 2. still use multiple FS with ODBC So anyone can help? BG Dome C.