[Freeswitch-users] Limits on number of concurrent registered users?

Hi all, i am preparing a setup where i would have a huge number of connected users via SIP/TLS . The amount of concurrent calls will not be such high. However he amount of concurrently registered users could be even of 15.000 . Are there some specific internal design/architectural limits of FreeSWITCH on the number of concurrent users? Fabio p.s. we'll try to do some stress testing next week